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Robert Williams is an internet application developer for the Salem Web Network.
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The opinions expressed herein are my own personal opinions and do not represent my employer's view in anyway.


Override Configuration Manager

Recently I have been working on ways to solve configuration issues in large, multi environment solutions. In the beginning, I simply wanted to store shared app settings and connection strings with a class library so I didn't have to keep copying common configuration settings from project to project within the same solution. Taking that a step further, I thought it would be great to auto detect the runtime environment and use the right app settings and connection strings from that shared configuration file. This all works great, but it has two major drawbacks: firstly, third party tools such as Elmah, and built in tools such as the Membership, Profile and Role Providers look no further that the built in ConfigurationManager object for appSettings and connection strings which forces us to subclass (Dynamically setting the Elmah connection string at runtime) or override their initialization (Setting Membership-Profile-Role provider's connection string at runtime) in order for them to work with our new settings. Not all third party tools will be as easy to fix. Secondly, all the developers working on the project must be trained to use the new techniques and always remember to use Core.Configuration.AppSettings["key"] instead of ConfigurationManager because ConfigurationManager.AppSettings["key"] may be null or hold the wrong value.

With that in mind, the next logical step was to find a way to override the built in ConfigurationManager ensuring that the Core.Configuration settings are fully integrated. In short: any call to ConfigurationManager.AppSettings or ConfigurationManager.ConnectionStrings should return the correct setting, whether that setting comes from the local web/app.config or the Core.Config. In order to do this it is assumed that if a setting appears both in the local app/web.config and the Core.Config files, then the value in the Core.Config file will be the value returned.

Download the latest version of the Williablog.Core project:

Williablog.Core.zip (110.11 kb)

Add a reference to it from your project (either to the project or the dll in the bin folder) and the first line in void Main() of your console Application or (if a web application) Application_Start()  in Global.asax should be:

Williablog.Core.Configuration.ConfigSystem.Install();

This will reinitialize the Configuration forcing it to rebuild the static cache of values but this time we are in control, and as a result we are able to effectively override the ConfigurationManager. Here is the code:

namespace Williablog.Core.Configuration

{

    using System;

    using System.Collections.Specialized;

    using System.Configuration;

    using System.Configuration.Internal;

    using System.Reflection;

 

    using Extensions;

 

    public sealed class ConfigSystem : IInternalConfigSystem

    {

        private static IInternalConfigSystem clientConfigSystem;

 

        private object appsettings;

 

        private object connectionStrings;

 

        /// <summary>

        /// Re-initializes the ConfigurationManager, allowing us to merge in the settings from Core.Config

        /// </summary>

        public static void Install()

        {

            FieldInfo[] fiStateValues = null;

            Type tInitState = typeof(System.Configuration.ConfigurationManager).GetNestedType("InitState", BindingFlags.NonPublic);

 

            if (null != tInitState)

            {

                fiStateValues = tInitState.GetFields();

            }

 

            FieldInfo fiInit = typeof(System.Configuration.ConfigurationManager).GetField("s_initState", BindingFlags.NonPublic | BindingFlags.Static);

            FieldInfo fiSystem = typeof(System.Configuration.ConfigurationManager).GetField("s_configSystem", BindingFlags.NonPublic | BindingFlags.Static);

 

            if (fiInit != null && fiSystem != null && null != fiStateValues)

            {

                fiInit.SetValue(null, fiStateValues[1].GetValue(null));

                fiSystem.SetValue(null, null);

            }

 

            ConfigSystem confSys = new ConfigSystem();

            Type configFactoryType = Type.GetType("System.Configuration.Internal.InternalConfigSettingsFactory, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", true);

            IInternalConfigSettingsFactory configSettingsFactory = (IInternalConfigSettingsFactory)Activator.CreateInstance(configFactoryType, true);

            configSettingsFactory.SetConfigurationSystem(confSys, false);

 

            Type clientConfigSystemType = Type.GetType("System.Configuration.ClientConfigurationSystem, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", true);

            clientConfigSystem = (IInternalConfigSystem)Activator.CreateInstance(clientConfigSystemType, true);

        }

 

        #region IInternalConfigSystem Members

 

        public object GetSection(string configKey)

        {

            // get the section from the default location (web.config or app.config)

            object section = clientConfigSystem.GetSection(configKey);

 

            switch (configKey)

            {

                case "appSettings":

                    if (this.appsettings != null)

                    {

                        return this.appsettings;

                    }

 

                    if (section is NameValueCollection)

                    {

                        // create a new collection because the underlying collection is read-only

                        var cfg = new NameValueCollection((NameValueCollection)section);

 

                        // merge the settings from core with the local appsettings

                        this.appsettings = cfg.Merge(Core.Configuration.ConfigurationManager.AppSettings);

                        section = this.appsettings;

                    }

 

                    break;

                case "connectionStrings":

                    if (this.connectionStrings != null)

                    {

                        return this.connectionStrings;

                    }

 

                    // create a new collection because the underlying collection is read-only

                    var cssc = new ConnectionStringSettingsCollection();

 

                    // copy the existing connection strings into the new collection

                    foreach (ConnectionStringSettings connectionStringSetting in ((ConnectionStringsSection)section).ConnectionStrings)

                    {

                        cssc.Add(connectionStringSetting);

                    }

 

                    // merge the settings from core with the local connectionStrings

                    cssc = cssc.Merge(ConfigurationManager.ConnectionStrings);

 

                    // Cannot simply return our ConnectionStringSettingsCollection as the calling routine expects a ConnectionStringsSection result

                    ConnectionStringsSection connectionStringsSection = new ConnectionStringsSection();

 

                    // Add our merged connection strings to the new ConnectionStringsSection

                    foreach (ConnectionStringSettings connectionStringSetting in cssc)

                    {

                        connectionStringsSection.ConnectionStrings.Add(connectionStringSetting);

                    }

 

                    this.connectionStrings = connectionStringsSection;

                    section = this.connectionStrings;

                    break;

            }

 

            return section;

        }

 

        public void RefreshConfig(string sectionName)

        {

            if (sectionName == "appSettings")

            {

                this.appsettings = null;

            }

 

            if (sectionName == "connectionStrings")

            {

                this.connectionStrings = null;

            }

 

            clientConfigSystem.RefreshConfig(sectionName);

        }

 

        public bool SupportsUserConfig

        {

            get { return clientConfigSystem.SupportsUserConfig; }

        }

 

        #endregion

    }

}

The code to actually merge our collections is implemented as Extension methods:

namespace Williablog.Core.Extensions

{

    using System;

    using System.Collections.Generic;

    using System.Collections.Specialized;

    using System.Configuration;

    using System.Linq;

    using System.Linq.Expressions;

    using System.Text;

 

    public static class IEnumerableExtensions

    {

        /// <summary>

        /// Merges two NameValueCollections.

        /// </summary>

        /// <param name="first"></param>

        /// <param name="second"></param>

        /// <remarks>Used by <see cref="Williablog.Core.Configuration.ConfigSystem">ConfigSystem</c> to merge AppSettings</remarks>

        public static NameValueCollection Merge(this NameValueCollection first, NameValueCollection second)

        {

            if (second == null)

            {

                return first;

            }

 

            foreach (string item in second)

            {

                if (first.AllKeys.Contains(item))

                {

                    // if first already contains this item, update it to the value of second

                    first[item] = second[item];

                }

                else

                {

                    // otherwise add it

                    first.Add(item, second[item]);

                }

            }

 

            return first;

        }

 

        /// <summary>

        /// Merges two ConnectionStringSettingsCollections.

        /// </summary>

        /// <param name="first"></param>

        /// <param name="second"></param>

        /// <remarks>Used by <see cref="Williablog.Core.Configuration.ConfigSystem">ConfigSystem</c> to merge ConnectionStrings</remarks>

        public static ConnectionStringSettingsCollection Merge(this ConnectionStringSettingsCollection first, ConnectionStringSettingsCollection second)

        {

            if (second == null)

            {

                return first;

            }

 

            foreach (ConnectionStringSettings item in second)

            {

                ConnectionStringSettings itemInSecond = item;

                ConnectionStringSettings existingItem = first.Cast<ConnectionStringSettings>().FirstOrDefault(x => x.Name == itemInSecond.Name);

 

                if (existingItem != null)

                {

                    first.Remove(item);

                }

 

                first.Add(item);

            }

 

            return first;

        }

    }

}

If we create a console application to test with, complete with it's own app.config file that looks like this:

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <appSettings>

    <add key="WebServiceUrl" value="http://webservices.yourserver.com/YourService.asmx"/>

    <add key="SmtpServer" value="smtp.yourmailserver.com"/>

    <add key="LocalOnly" value="This is from the local app.config"/>

  </appSettings>

  <connectionStrings>

    <add name="AppData" connectionString="data source=Audi01;initial catalog=MyDB;User ID=User;Password=Password;" providerName="System.Data.SqlClient"/>

    <add name="ElmahDB" connectionString="Database=ELMAH;Server=Audi02;User=User;Pwd=Password;" providerName="System.Data.SqlClient"/>

  </connectionStrings>

</configuration>

And run it with the following code:

        static void Main(string[] args)

        {

            ConfigSystem.Install();

 

            Console.WriteLine(System.Configuration.ConfigurationManager.AppSettings["SmtpServer"]);

            Console.WriteLine(System.Configuration.ConfigurationManager.AppSettings["LocalOnly"]);

            Console.WriteLine(System.Configuration.ConfigurationManager.ConnectionStrings["AppData"]);

        }

 

The output is:

smtp.yourlocalmailserver.com

This is from the local app.config
data source=Ford01;initial catalog=MyDB;User ID=User;Password=Password;

With the exception of the middle one (LocalOnly) all of these settings come from Williablog.Core.Config, not the local app.config proving that the config files were successfully merged.

The ConfigSystem class could be modified to retrive the additional appsettings from the registry, from a database or from any other source you care to use.

I'd like to thank the contributers/authors of the following articles which I found very helpful:

http://stackoverflow.com/questions/158783/is-there-a-way-to-override-configurationmanager-appsettings

http://andypook.blogspot.com/2007/07/overriding-configurationmanager.html


Posted by Williarob on Monday, March 29, 2010 7:13 AM
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ISO to USB Flash Drive

If you have a laptop or a mini computer without a cd/dvd-rom drive, or your CD/DVD-ROM drive simply broke but you need to use a bootable cd, you can substitute a USB flash memory stick or pen drive in its place. Obviously, if you don't already have an ISO image of your disc, you will need to use another computer that has a functioning CD/DVD-ROM drive to create one. To do this, use some sort of CD Burning software such as Slysoft CloneCD, Nero Burning Rom, etc. to create your ISO image. Then all you need to do download a tool like UNetbootin or BootMyIso and follow the onscreen instructions to make your bootable Flash drive. These tools were designed to create Live versions of Linux, but they do work equally well with any bootable ISO image such as your Windows operating system disk, or Symantec Ghost Recovery disc. Just to be clear, they will not make Windows run live from a USB stick in the same way you can run Ubuntu from a flash drive, but they will allow you to boot your PC into the setup screens required to install Windows on your system in just the same way you could with the original CD and an optical drive.


Posted by Williarob on Monday, March 22, 2010 9:43 AM
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Dynamically setting the Elmah connection string at runtime

If you have read my other articles about setting the SQL Membership provider's connection string at runtime, or automatically detecting the server name and using the appropriate connection strings then it will come as no surprise to see that I also had to find a way to set the Elmah connection string property dynamically too. If you are reading this, I'll assume that you already know what Elmah is and how to configure it. The problem then is simply that the connection string is supplied in the <elmah><errorLog> section of the web.config using a connection string name, and that while the name may the same in production as it is in development, chances are high that the connection string itself is different. The connection string property is readonly, so you can't change it at runtime. One solution is to create an elmah.config file, and use Finalbuilder or a web deployment project to change the path to that file when publishing, but if you like the AdvancedSettingsManager class I created and want to use that to set it you'll need to use a custom ErrorLog. Fortunately, Elmah is open source, so I simply downloaded the source, took a look at their SqlErrorLog class and then copied and pasted most of the code from that class into my own project, modifying it only slightly to suit my own needs.

In the end, the only changes I really needed to make were to pull the connectionstring by name from my AdvancedSettingsManager class and to copy a couple of helper functions locally into this class since they were marked as internal and therefore unavailable outside of the Elmah solution. I also removed the conditional compilation flags that only applied to .Net 1.x since this was a .Net 3.5 project.

namespace Williablog.Core.Providers

{

    #region Imports

 

    using System;

    using System.Configuration;

    using System.Data;

    using System.Data.SqlClient;

    using System.Diagnostics;

    using System.Threading;

    using System.Xml;

 

    using Elmah;

 

    using ApplicationException = System.ApplicationException;

    using IDictionary = System.Collections.IDictionary;

    using IList = System.Collections.IList;

 

    #endregion

 

    public class SqlErrorLog : ErrorLog

    {

        private readonly string _connectionString;

 

        private const int _maxAppNameLength = 60;

 

        private delegate RV Function<RV, A>(A a);

 

        ///<summary>

        /// Initializes a new instance of the <see cref="SqlErrorLog"/> class

        /// using a dictionary of configured settings.

        ///</summary>

 

        public SqlErrorLog(IDictionary config)

        {

            if (config == null)

                throw new ArgumentNullException("config");

 

// Start Williablog changes

 

            string connectionStringName = (string)config["connectionStringName"] jQuery1520895691458676146_1360618079128 string.Empty;

 

            string connectionString = string.Empty;

 

            if (connectionStringName.Length > 0)

            {

 

            //

            // Write your code here to get the connection string as a ConnectionStringSettings object

 

            //

                ConnectionStringSettings settings = Williablog.Core.Configuration.AdvancedSettingsManager.SettingsFactory().ConnectionStrings["ErrorDB"];

                if (settings == null)

                    throw new ApplicationException("Connection string is missing for the SQL error log.");

 

                connectionString = settings.ConnectionString ?? string.Empty;

            }

 

// End Williablog changes

 

            //

            // If there is no connection string to use then throw an

            // exception to abort construction.

            //

 

            if (connectionString.Length == 0)

                throw new ApplicationException("Connection string is missing for the SQL error log.");

 

            _connectionString = connectionString;

 

            //

            // Set the application name as this implementation provides

            // per-application isolation over a single store.

            //

 

            string appName = NullString((string)config["applicationName"]);

 

            if (appName.Length > _maxAppNameLength)

            {

                throw new ApplicationException(string.Format(

                    "Application name is too long. Maximum length allowed is {0} characters.",

                    _maxAppNameLength.ToString("N0")));

            }

 

            ApplicationName = appName;

        }

 

        ///<summary>

        /// Initializes a new instance of the <see cref="SqlErrorLog"/> class

        /// to use a specific connection string for connecting to the database.

        ///</summary>

 

        public SqlErrorLog(string connectionString)

        {

            if (connectionString == null)

                throw new ArgumentNullException("connectionString");

 

            if (connectionString.Length == 0)

                throw new ArgumentException(null, "connectionString");

 

            _connectionString = connectionString;

        }

 

        ///<summary>

        /// Gets the name of this error log implementation.

        ///</summary>

 

        public override string Name

        {

            get { return "Microsoft SQL Server Error Log"; }

        }

 

        ///<summary>

        /// Gets the connection string used by the log to connect to the database.

        ///</summary>

 

        public virtual string ConnectionString

        {

            get { return _connectionString; }

        }

 

        ///<summary>

        /// Logs an error to the database.

        ///</summary>

        ///<remarks>

        /// Use the stored procedure called by this implementation to set a

        /// policy on how long errors are kept in the log. The default

        /// implementation stores all errors for an indefinite time.

        ///</remarks>

 

        public override string Log(Error error)

        {

            if (error == null)

                throw new ArgumentNullException("error");

 

            string errorXml = ErrorXml.EncodeString(error);

            Guid id = Guid.NewGuid();

 

            using (SqlConnection connection = new SqlConnection(this.ConnectionString))

            using (SqlCommand command = Commands.LogError(

                id, this.ApplicationName,

                error.HostName, error.Type, error.Source, error.Message, error.User,

                error.StatusCode, error.Time.ToUniversalTime(), errorXml))

            {

                command.Connection = connection;

                connection.Open();

                command.ExecuteNonQuery();

                return id.ToString();

            }

        }

 

        ///<summary>

        /// Returns a page of errors from the databse in descending order

        /// of logged time.

        ///</summary>

 

        public override int GetErrors(int pageIndex, int pageSize, IList errorEntryList)

        {

            if (pageIndex < 0)

                throw new ArgumentOutOfRangeException("pageIndex", pageIndex, null);

 

            if (pageSize < 0)

                throw new ArgumentOutOfRangeException("pageSize", pageSize, null);

 

            using (SqlConnection connection = new SqlConnection(this.ConnectionString))

            using (SqlCommand command = Commands.GetErrorsXml(this.ApplicationName, pageIndex, pageSize))

            {

                command.Connection = connection;

                connection.Open();

 

                XmlReader reader = command.ExecuteXmlReader();

 

                try

                {

                    ErrorsXmlToList(reader, errorEntryList);

                }

                finally

                {

                    reader.Close();

                }

 

                int total;

                Commands.GetErrorsXmlOutputs(command, out total);

                return total;

            }

        }

 

        ///<summary>

        /// Begins an asynchronous version of <see cref="GetErrors"/>.

        ///</summary>

 

        public override IAsyncResult BeginGetErrors(int pageIndex, int pageSize, IList errorEntryList,

            AsyncCallback asyncCallback, object asyncState)

        {

            if (pageIndex < 0)

                throw new ArgumentOutOfRangeException("pageIndex", pageIndex, null);

 

            if (pageSize < 0)

                throw new ArgumentOutOfRangeException("pageSize", pageSize, null);

 

            //

            // Modify the connection string on the fly to support async

            // processing otherwise the asynchronous methods on the

            // SqlCommand will throw an exception. This ensures the

            // right behavior regardless of whether configured

            // connection string sets the Async option to true or not.

            //

 

            SqlConnectionStringBuilder csb = new SqlConnectionStringBuilder(this.ConnectionString);

            csb.AsynchronousProcessing = true;

            SqlConnection connection = new SqlConnection(csb.ConnectionString);

 

            //

            // Create the command object with input parameters initialized

            // and setup to call the stored procedure.

            //

 

            SqlCommand command = Commands.GetErrorsXml(this.ApplicationName, pageIndex, pageSize);

            command.Connection = connection;

 

            //

            // Create a closure to handle the ending of the async operation

            // and retrieve results.

            //

 

            AsyncResultWrapper asyncResult = null;

 

            Function<int, IAsyncResult> endHandler = delegate

            {

                Debug.Assert(asyncResult != null);

 

                using (connection)

                using (command)

                {

                    using (XmlReader reader = command.EndExecuteXmlReader(asyncResult.InnerResult))

                        ErrorsXmlToList(reader, errorEntryList);

 

                    int total;

                    Commands.GetErrorsXmlOutputs(command, out total);

                    return total;

                }

            };

 

            //

            // Open the connenction and execute the command asynchronously,

            // returning an IAsyncResult that wrap the downstream one. This

            // is needed to be able to send our own AsyncState object to

            // the downstream IAsyncResult object. In order to preserve the

            // one sent by caller, we need to maintain and return it from

            // our wrapper.

            //

 

            try

            {

                connection.Open();

 

                asyncResult = new AsyncResultWrapper(

                    command.BeginExecuteXmlReader(

                        asyncCallback != null ? /* thunk */ delegate { asyncCallback(asyncResult); } : (AsyncCallback)null,

                        endHandler), asyncState);

 

                return asyncResult;

            }

            catch (Exception)

            {

                connection.Dispose();

                throw;

            }

        }

 

        ///<summary>

        /// Ends an asynchronous version of <see cref="ErrorLog.GetErrors"/>.

        ///</summary>

 

        public override int EndGetErrors(IAsyncResult asyncResult)

        {

            if (asyncResult == null)

                throw new ArgumentNullException("asyncResult");

 

            AsyncResultWrapper wrapper = asyncResult as AsyncResultWrapper;

 

            if (wrapper == null)

                throw new ArgumentException("Unexepcted IAsyncResult type.", "asyncResult");

 

            Function<int, IAsyncResult> endHandler = (Function<int, IAsyncResult>)wrapper.InnerResult.AsyncState;

            return endHandler(wrapper.InnerResult);

        }

 

        private void ErrorsXmlToList(XmlReader reader, IList errorEntryList)

        {

            Debug.Assert(reader != null);

 

            if (errorEntryList != null)

            {

                while (reader.IsStartElement("error"))

                {

                    string id = reader.GetAttribute("errorId");

                    Error error = ErrorXml.Decode(reader);

                    errorEntryList.Add(new ErrorLogEntry(this, id, error));

                }

            }

        }

 

        ///<summary>

        /// Returns the specified error from the database, or null

        /// if it does not exist.

        ///</summary>

        public override ErrorLogEntry GetError(string id)

        {

            if (id == null)

                throw new ArgumentNullException("id");

 

            if (id.Length == 0)

                throw new ArgumentException(null, "id");

 

            Guid errorGuid;

 

            try

            {

                errorGuid = new Guid(id);

            }

            catch (FormatException e)

            {

                throw new ArgumentException(e.Message, "id", e);

            }

 

            string errorXml;

 

            using (SqlConnection connection = new SqlConnection(this.ConnectionString))

            using (SqlCommand command = Commands.GetErrorXml(this.ApplicationName, errorGuid))

            {

                command.Connection = connection;

                connection.Open();

                errorXml = (string)command.ExecuteScalar();

            }

 

            if (errorXml == null)

                return null;

 

            Error error = ErrorXml.DecodeString(errorXml);

            return new ErrorLogEntry(this, id, error);

        }

 

// These utility functions were marked as internal, so I had to copy them locally

        public static string NullString(string s)

        {

            return s ?? string.Empty;

        }

 

        public static string EmptyString(string s, string filler)

        {

            return NullString(s).Length == 0 ? filler : s;

        }

 

// End

 

        private sealed class Commands

        {

            private Commands() { }

 

            public static SqlCommand LogError(

                Guid id,

                string appName,

                string hostName,

                string typeName,

                string source,

                string message,

                string user,

                int statusCode,

                DateTime time,

                string xml)

            {

                SqlCommand command = new SqlCommand("ELMAH_LogError");

                command.CommandType = CommandType.StoredProcedure;

 

                SqlParameterCollection parameters = command.Parameters;

 

                parameters.Add("@ErrorId", SqlDbType.UniqueIdentifier).Value = id;

                parameters.Add("@Application", SqlDbType.NVarChar, _maxAppNameLength).Value = appName;

                parameters.Add("@Host", SqlDbType.NVarChar, 30).Value = hostName;

                parameters.Add("@Type", SqlDbType.NVarChar, 100).Value = typeName;

                parameters.Add("@Source", SqlDbType.NVarChar, 60).Value = source;

                parameters.Add("@Message", SqlDbType.NVarChar, 500).Value = message;

                parameters.Add("@User", SqlDbType.NVarChar, 50).Value = user;

                parameters.Add("@AllXml", SqlDbType.NText).Value = xml;

                parameters.Add("@StatusCode", SqlDbType.Int).Value = statusCode;

                parameters.Add("@TimeUtc", SqlDbType.DateTime).Value = time;

 

                return command;

            }

 

            public static SqlCommand GetErrorXml(string appName, Guid id)

            {

                SqlCommand command = new SqlCommand("ELMAH_GetErrorXml");

                command.CommandType = CommandType.StoredProcedure;

 

                SqlParameterCollection parameters = command.Parameters;

                parameters.Add("@Application", SqlDbType.NVarChar, _maxAppNameLength).Value = appName;

                parameters.Add("@ErrorId", SqlDbType.UniqueIdentifier).Value = id;

 

                return command;

            }

 

            public static SqlCommand GetErrorsXml(string appName, int pageIndex, int pageSize)

            {

                SqlCommand command = new SqlCommand("ELMAH_GetErrorsXml");

                command.CommandType = CommandType.StoredProcedure;

 

                SqlParameterCollection parameters = command.Parameters;

 

                parameters.Add("@Application", SqlDbType.NVarChar, _maxAppNameLength).Value = appName;

                parameters.Add("@PageIndex", SqlDbType.Int).Value = pageIndex;

                parameters.Add("@PageSize", SqlDbType.Int).Value = pageSize;

                parameters.Add("@TotalCount", SqlDbType.Int).Direction = ParameterDirection.Output;

 

                return command;

            }

 

            public static void GetErrorsXmlOutputs(SqlCommand command, out int totalCount)

            {

                Debug.Assert(command != null);

 

                totalCount = (int)command.Parameters["@TotalCount"].Value;

            }

        }

 

        ///<summary>

        /// An <see cref="IAsyncResult"/> implementation that wraps another.

        ///</summary>

 

        private sealed class AsyncResultWrapper : IAsyncResult

        {

            private readonly IAsyncResult _inner;

            private readonly object _asyncState;

 

            public AsyncResultWrapper(IAsyncResult inner, object asyncState)

            {

                _inner = inner;

                _asyncState = asyncState;

            }

 

            public IAsyncResult InnerResult

            {

                get { return _inner; }

            }

 

            public bool IsCompleted

            {

                get { return _inner.IsCompleted; }

            }

 

            public WaitHandle AsyncWaitHandle

            {

                get { return _inner.AsyncWaitHandle; }

            }

 

            public object AsyncState

            {

                get { return _asyncState; }

            }

 

            public bool CompletedSynchronously

            {

                get { return _inner.CompletedSynchronously; }

            }

        }

    }

}

Finally all you need to do is modify the web.config file to use this SqlErrorlog instead of the built in one:

  <elmah>  

    <errorLogtype="Williablog.Core.Providers.SqlErrorLog, Williablog.Core"

            connectionStringName="ErrorDB" />

<!--

            Other elmah settings ommitted for clarity

-->

  </elmah>

Note: You will still need to reference the Elmah dll in your project as all we have done here is subclass the ErrorLog type, all of the remaining Elmah goodness is still locked up inside the elmah dll. You could of course make these changes directly inside the elmah source code and recompile it to produce your own version of the elmah dll, but these changes were project specific and I didn't want to end up one day with dozens of project specific versions of the elmah dll. This way, the project specific code stays with the project and the elmah dll remains untouched.

Edit: As Stan Shillis points out on the Code project version of this article, there is a cleaner, simpler approach that will allow you to keep up with new versions of Elmah without editing the source of each release:

Instead of fully rewriting Elmah's SQLErrorLog you can inherit it and override just the ConnectingString property. This way you don't loose benefits of Elmah code updates.
 
Sample code:

public class CustomSqlErrorLog : Elmah.SqlErrorLog
{
	protected string connectionStringName;
	public CustomSqlErrorLog(IDictionary config) : base(config)
	{
		connectionStringName = (string)config["connectionStringName"];
	}
 
	public override string ConnectionString {
		get { return CustomConfigManager.ConnectionStrings[connectionStringName]; }
	}
}

 
The only caveat is that you still have to have that connection string entry in your web.config ConnectionStrings sections because SqlErrorLog base class checks for its existence. It won't actually use the connection string from config file but it needs to be there for it work properly.
 
Sample config:
 

<elmah>
<errorLog type="YourNameSpace.CustomSqlErrorLog, YourAssembly" connectionStringName="Elmah" applicationName="CustomApp" />
</elmah>
 
<connectionStrings>
    <add name="Elmah" connectionString="do.not.change.or.remove.this" providerName="System.Data.SqlClient" />
</connectionStrings>

Categories: ASP.Net | C# | CodeProject
Posted by Williarob on Thursday, March 18, 2010 12:10 PM
Permalink | Comments (0) | Post RSSRSS comment feed

Auto detect the runtime environment and use the right app settings and connection strings

There are many ways to manage the problem of connection string and app settings substitution in the web.config / app.config files when publishing to different environments (e.g. QA and Production servers). In the past I have made use of the Web Deployment project's ability to replace the appsettings and connectionstrings sections, I have experimented with batch files, Build events, conditional compilation and used the extremely powerful FinalBuilder. However, my prefered solution is to have a single shared .config file with all the possible settings in it (so you only have to open one file to change any of the settings) then have the executing application automatically detect the environment and use the correct settings every time.

The technique dicussed below builds on that of an earlier article which described how to centralize your shared application settings and connection strings in a common class library. It also assumes that you know the machine names of your development, QA and production servers. Obviously servers get replaced from time to time and websites sometimes get moved from one server to another, but it has been my experience that there is usually some sort of common naming convention used on servers and web farms, and knowing that convention should be good enough. Even this is not the case, the Development, QA and Production server names are stored in an app setting so you can easily change them at any time if necessary. For this example, the assumption is that the development servers are all named something like "Squirrel01", "Squirrel02", the QA boxes are "Fox01", "Fox02", and the production (farm) boxes are "Rabbit01x", "Rabbit01y", "Rabbit02x", "Rabbit02y", etc. With this in mind, it is necessary only to look for the words "Rabbit", "Fox" or "Squirrel" in the machine name we are running on to identify the current environment and know which section of our config file to use. If none of these names is found, we shall assume the app is running on the localhost of a developer's computer, and use those settings. I should point out that it is possible to for a server to be configured in such a way as to prevent Environment.MachineName from returning a value, in which case this technique simply will not work, so before you start trying to integrate this code into your solution, I recommend you craete a quick test.aspx page or console app that simply does a Response.Write(Environment.MachineName)/Console.WriteLine(Environment.MachineName) and run it on your servers.

First, let's setup our .config file:

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <configSections>

    <sectionGroup name="Localhost" type="Williablog.Core.Configuration.EnvironmentSectionGroup, Williablog.Core">

      <section name="appSettings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" restartOnExternalChanges="false" requirePermission="false" />

      <section name="connectionStrings" type="System.Configuration.ConnectionStringsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" requirePermission="false" />

    </sectionGroup>

 

    <sectionGroup name="Dev" type="Williablog.Core.Configuration.EnvironmentSectionGroup, Williablog.Core">

      <section name="appSettings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" restartOnExternalChanges="false" requirePermission="false" />

      <section name="connectionStrings" type="System.Configuration.ConnectionStringsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" requirePermission="false" />

    </sectionGroup>

 

    <sectionGroup name="Qa" type="Williablog.Core.Configuration.EnvironmentSectionGroup, Williablog.Core">

      <section name="appSettings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" restartOnExternalChanges="false" requirePermission="false" />

      <section name="connectionStrings" type="System.Configuration.ConnectionStringsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" requirePermission="false" />

    </sectionGroup>

 

    <sectionGroup name="Production" type="Williablog.Core.Configuration.EnvironmentSectionGroup, Williablog.Core">

      <section name="appSettings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" restartOnExternalChanges="false" requirePermission="false" />

      <section name="connectionStrings" type="System.Configuration.ConnectionStringsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" requirePermission="false" />

    </sectionGroup>

  </configSections>

 

  <Localhost>

    <appSettings>

      <add key="WebServiceUrl" value="http://webservices.squirrel01.yourserver.com/YourService.asmx"/>

      <add key="SmtpServer" value="smtp.yourlocalmailserver.com"/>

    </appSettings>

    <connectionStrings>

      <add name="AppData" connectionString="data source=Ford01;initial catalog=MyDB;User ID=User;Password=Password;" providerName="System.Data.SqlClient"/>

      <add name="ElmahDB" connectionString="Database=ELMAH;Server=Ford02;User=User;Pwd=Password;" providerName="System.Data.SqlClient"/>

    </connectionStrings>

  </Localhost>

 

  <Dev>

    <appSettings>

      <add key="WebServiceUrl" value="http://webservices.squirrel01.yourserver.com/YourService.asmx"/>

      <add key="SmtpServer" value="smtp.yourlocalmailserver.com"/>

    </appSettings>

    <connectionStrings>

      <add name="AppData" connectionString="data source=Ford01;initial catalog=MyDB;User ID=User;Password=Password;" providerName="System.Data.SqlClient"/>

      <add name="ElmahDB" connectionString="Database=ELMAH;Server=Ford02;User=User;Pwd=Password;" providerName="System.Data.SqlClient"/>

    </connectionStrings>

  </Dev>

 

  <Qa>

    <appSettings>

      <add key="WebServiceUrl" value="http://webservices.Fox01.yourserver.com/YourService.asmx"/>

      <add key="SmtpServer" value="smtp.yourlocalmailserver.com"/>

    </appSettings>

    <connectionStrings>

      <add name="AppData" connectionString="data source=BMW01;initial catalog=MyDB;User ID=User;Password=Password;" providerName="System.Data.SqlClient"/>

      <add name="ElmahDB" connectionString="Database=ELMAH;Server=BMW02;User=User;Pwd=Password;" providerName="System.Data.SqlClient"/>

    </connectionStrings>

  </Qa>

 

  <Production>

    <appSettings>

      <add key="WebServiceUrl" value="http://webservices.yourserver.com/YourService.asmx"/>

      <add key="SmtpServer" value="smtp.yourmailserver.com"/>

    </appSettings>

    <connectionStrings>

      <add name="AppData" connectionString="data source=Audi01;initial catalog=MyDB;User ID=User;Password=Password;" providerName="System.Data.SqlClient"/>

      <add name="ElmahDB" connectionString="Database=ELMAH;Server=Audi02;User=User;Pwd=Password;" providerName="System.Data.SqlClient"/>

    </connectionStrings>

  </Production>

 

  <appSettings>

    <!-- Global/common appsettings can go here -->

    <add key="Test" value="Hello World"/>

 

    <add key="DevelopmentNames" value="SQUIRREL"/>

    <add key="ProductionNames" value="RABBIT"/>

    <add key="QANames" value="FOX"/>

    <add key="EnvironmentOverride" value=""/>

    <!-- /Dev | /Localhost | /Production | (blank)-->

 

  </appSettings>

</configuration>

As you can see, the first thing we do in the config file is declare four section groups, "LocalHost", "Dev", "Qa" and "Production". I chose to create a custom SectionGroup since this allowed me to strongly type the expected sections within it, greatly simplifying the code required to access those sections. All the EnvironmentSectionGroup class does, is inherit ConfigurationSectionGroup and declare two properties:

namespace Williablog.Core.Configuration

{

    using System.Configuration;

 

    public class EnvironmentSectionGroup : ConfigurationSectionGroup

    {

 

        #region Properties

 

        [ConfigurationProperty("appSettings")]

        public AppSettingsSection AppSettings

        {

            get

            {

                return (AppSettingsSection)Sections["appSettings"];

            }

        }

 

        [ConfigurationProperty("connectionStrings")]

        public ConnectionStringsSection ConnectionStrings

        {

            get

            {

                return (ConnectionStringsSection)Sections["connectionStrings"];

            }

        }

 

        #endregion

 

    }

}

Next, we create the sections for localhost, development, qa and production, each of which has its own appSettings and connectionStrings sections. These are of the same type as the connectionStrings and appSettings found in any .config file, meaning we don't need to write any additional code to fully utilise these sections - no traversing of primitive xmlNodes or anything like that to get the connectionstrings from that section. Finally we add the expected, normal appsettings section which in this case will provide the global or common appsettings that are shared by all environments. It is here that we store the server names that will help us identify where the app is currently executing. The EnvironmentOverride setting is an added bonus -it allows you to use all of qa or production settings while running on localhost which helps you debug those "well it works on my machine" situations without having to manually change all of the settings for localhost.

Building on the BasicSettingsManager we built earlier we simply add some code to determine the machine name we are running on and return the appSettings and connectionStrings sections appropriate to that environment:

namespace Williablog.Core.Configuration

{

    using System;

    using System.Collections.Specialized;

    using System.Configuration;

    using System.IO;

    using System.Linq;

 

    public class AdvancedSettingsManager

    {

        #region fields

 

        private const string ConfigurationFileName = "Williablog.Core.config";

 

        /// <summary>

        /// default path to the config file that contains the settings we are using

        /// </summary>

        private static string configurationFile;

 

        /// <summary>

        /// Stores an instance of this class, to cut down on I/O: No need to keep re-loading that config file

        /// </summary>

        /// <remarks>Cannot use system.web.caching since agents will not have access to this by default, so use static member instead.</remarks>

        private static AdvancedSettingsManager instance;

 

        /// <summary>

        /// Settings Environment

        /// </summary>

        private static string settingsEnvironment;

 

        private static EnvironmentSectionGroup currentSettingsGroup;

 

        #endregion

 

        #region Constructors

 

        private AdvancedSettingsManager()

        {

            ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();

 

            fileMap.ExeConfigFilename = configurationFile;

 

            Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);

 

            settingsEnvironment = "Localhost"; // default to localhost

 

            // get the name of the machine we are currently running on

            string machineName = Environment.MachineName.ToUpper();

 

            // compare to known environment machine names

            if (config.AppSettings.Settings["ProductionNames"].Value.Split(',').Where(x => machineName.Contains(x)).Count() > 0)

            {

                settingsEnvironment = "Production";

            }

            else if (config.AppSettings.Settings["QANames"].Value.Split(',').Where(x => machineName.Contains(x)).Count() > 0)

            {

                settingsEnvironment = "Qa";

            }

            else if (config.AppSettings.Settings["DevelopmentNames"].Value.Split(',').Where(x => machineName.Contains(x)).Count() > 0)

            {

                settingsEnvironment = "Dev";

            }

 

            // If there is a value in the EnvironmentOverride appsetting, ignore results of auto detection and set it here

            // This allows us to hit production data from localhost without monkeying with all the config settings.

            if (!string.IsNullOrEmpty(config.AppSettings.Settings["EnvironmentOverride"].Value))

            {

                settingsEnvironment = config.AppSettings.Settings["EnvironmentOverride"].Value;

            }

 

            // Get the name of the section we are using in this environment & load the appropriate section of the config file

            currentSettingsGroup = config.GetSectionGroup(SettingsEnvironment) as EnvironmentSectionGroup;

        }

 

        #endregion

 

        #region Properties

 

        /// <summary>

        /// Returns the name of the current environment

        /// </summary>

        public string SettingsEnvironment

        {

            get

            {

                return settingsEnvironment;

            }

        }

 

        /// <summary>

        /// Returns the ConnectionStrings section

        /// </summary>

        public ConnectionStringSettingsCollection ConnectionStrings

        {

            get

            {

                return currentSettingsGroup.ConnectionStrings.ConnectionStrings;

            }

        }

 

        /// <summary>

        /// Returns the AppSettings Section

        /// </summary>

        public NameValueCollection AppSettings

        {

            get

            {

                NameValueCollection settings = new NameValueCollection();

                foreach (KeyValueConfigurationElement element in currentSettingsGroup.AppSettings.Settings)

                {

                    settings.Add(element.Key, element.Value);

                }

 

                return settings;

            }

        }

 

        #endregion

 

        #region static factory methods

 

        /// <summary>

        /// Public factory method

        /// </summary>

        /// <returns></returns>

        public static AdvancedSettingsManager SettingsFactory()

        {

            // If there is a bin folder, such as in web projects look for the config file there first

            if (Directory.Exists(AppDomain.CurrentDomain.BaseDirectory + @"\bin"))

            {

                configurationFile = string.Format(@"{0}\bin\{1}", AppDomain.CurrentDomain.BaseDirectory, ConfigurationFileName);

            }

            else

            {

                // agents, for example, won't have a bin folder in production

                configurationFile = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, ConfigurationFileName);

            }

 

            // If we still cannot find it, quit now!

            if (!File.Exists(configurationFile))

            {

                throw new FileNotFoundException(configurationFile);

            }

 

            return CreateSettingsFactoryInternal();

        }

 

        /// <summary>

        /// Overload that allows you to pass in the full path and filename of the config file you want to use.

        /// </summary>

        /// <param name="fullPathToConfigFile"></param>

        /// <returns></returns>

        public static AdvancedSettingsManager SettingsFactory(string fullPathToConfigFile)

        {

            configurationFile = fullPathToConfigFile;

            return CreateSettingsFactoryInternal();

        }

 

        /// <summary>internal Factory Method

        /// </summary>

        /// <returns>ConfigurationSettings object

        /// </returns>

        internal static AdvancedSettingsManager CreateSettingsFactoryInternal()

        {

            // If we havent created an instance yet, do so now

            if (instance == null)

            {

                instance = new AdvancedSettingsManager();

            }

 

            return instance;

        }

 

        #endregion

    }

}

As before you can then access the appSettings of the Core.Config from any of your projects like so:

Console.WriteLine(Williablog.Core.Configuration.AdvancedSettingsManager.SettingsFactory().AppSettings["Test"]);

To make this work, you will need to add a reference to System.Configuration. If the config file and Settings manager code is to be part of a class library, you will need to set the "Copy to Output Directory" property of your .config file to "Copy always"and add a reference to System.Configuration to each of your projects.

Download the Williablog.Core project: Williablog.Core.zip (100.77 kb)


Posted by Williarob on Thursday, March 18, 2010 9:00 AM
Permalink | Comments (0) | Post RSSRSS comment feed

How to store shared app settings and connection strings with your class library

When working on enterprise level, multi-tiered .Net applications it is not uncommon to want to create a shared class library, that may be used in multiple related projects. For example, let's suppose you are building a public website, a separate private intranet website used by company staff to manage the public site, and one or more console applications that may run as scheduled tasks related to both sites. You may have an console application that creates and emails reports about sales and other data, and another app that encodes video or audio that is uploaded to your site. Finally, you probably have another project for unit tests.

Since all of these projects will be working with the same database you also have a class library in your solution acting as your datalayer, and perhaps another Core library that contains other shared components. Each of these projects has it's own web.config or app.config file, and you had to copy and paste your connection string, smtp server data, and various other appSettings required by all the projects into every .config file. You may be inspired to add a new .config file to your Core library, and store all of the shared appsettings and connection strings in that one central location. If you then delete all of these settings from the other .config files you'll quickly realize that everything breaks. Even setting the "Copy to Output Directory" property of your Core.config file to "Copy always" doesn't fix this. The reason for this of course is that .Net always looks to the host application for the settings.

The solution is to add some code to your Core project that explicitly loads the Core.config file, reads in the data and makes the results available to all the other projects. That code might look something like this:

namespace Williablog.Core.Configuration

{

    using System;

    using System.Collections.Specialized;

    using System.Configuration;

    using System.IO;

 

    public class BasicSettingsManager

    {

        #region fields

 

        private const string ConfigurationFileName = "Williablog.Core.config";

 

        /// <summary>

        /// default path to the config file that contains the settings we are using

        /// </summary>

        private static string configurationFile;

 

        /// <summary>

        /// Stores an instance of this class, to cut down on I/O: No need to keep re-loading that config file

        /// </summary>

        /// <remarks>Cannot use system.web.caching since agents will not have access to this by default, so use static member instead.</remarks>

        private static BasicSettingsManager instance;

 

        private static Configuration config;

 

        #endregion

 

        #region Constructors

 

        private BasicSettingsManager()

        {

            ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();

            fileMap.ExeConfigFilename = configurationFile;

            config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);

        }

 

        #endregion

 

        #region Properties

 

        /// <summary>

        /// Returns the ConnectionStrings section

        /// </summary>

        public ConnectionStringSettingsCollection ConnectionStrings

        {

            get

            {

                return config.ConnectionStrings.ConnectionStrings;

            }

        }

 

        /// <summary>

        /// Returns the AppSettings Section

        /// </summary>

        public NameValueCollection AppSettings

        {

            get

            {

                NameValueCollection settings = new NameValueCollection();

                foreach (KeyValueConfigurationElement element in config.AppSettings.Settings)

                {

                    settings.Add(element.Key, element.Value);

                }

 

                return settings;

            }

        }

 

        #endregion

 

        #region static factory methods

 

        /// <summary>

        /// Public factory method

        /// </summary>

        /// <returns></returns>

        public static BasicSettingsManager SettingsFactory()

        {

            // If there is a bin folder, such as in web projects look for the config file there first

            if (Directory.Exists(AppDomain.CurrentDomain.BaseDirectory + @"\bin"))

            {

                configurationFile = string.Format(@"{0}\bin\{1}", AppDomain.CurrentDomain.BaseDirectory, ConfigurationFileName);

            }

            else

            {

                // agents, for example, won't have a bin folder in production

                configurationFile = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, ConfigurationFileName);

            }

 

            // If we still cannot find it, quit now!

            if (!File.Exists(configurationFile))

            {

                throw new FileNotFoundException(configurationFile);

            }

 

            return CreateSettingsFactoryInternal();

        }

 

        /// <summary>

        /// Overload that allows you to pass in the full path and filename of the config file you want to use.

        /// </summary>

        /// <param name="fullPathToConfigFile"></param>

        /// <returns></returns>

        public static BasicSettingsManager SettingsFactory(string fullPathToConfigFile)

        {

            configurationFile = fullPathToConfigFile;

            return CreateSettingsFactoryInternal();

        }

 

        /// <summary>internal Factory Method

        /// </summary>

        /// <returns>ConfigurationSettings object

        /// </returns>

        internal static BasicSettingsManager CreateSettingsFactoryInternal()

        {

            // If we havent created an instance yet, do so now

            if (instance == null)

            {

                instance = new BasicSettingsManager();

            }

 

            return instance;

        }

 

        #endregion

    }

}

You can then access the appSettings of Core.Config from any of your projects like so:

Console.WriteLine(Williablog.Core.Configuration.BasicSettingsManager.SettingsFactory().AppSettings["Key"]);

To make this work, you will need to set the "Copy to Output Directory" property of your Core.config file to "Copy always"and add a reference to System.Configuration to each of your projects.

We shall take this a step further next time and expand on this technique to enable your Core project to automatically detect wether it is running on localhost, a development environment, QA, or production, and to return the appropriate connection strings and settings for that environment.


Posted by Williarob on Thursday, March 18, 2010 8:08 AM
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Use lambda expressions to aggregate values into a delimited string

Let's say you need to aggregate one value from each object in a list into a single string. For Example, you want to send an e-mail to a set of customers. This requires a string with the email addresses seperated by a semicolon (;). The following code will create a generic List of Books, and provide a method ListAllEmails() that will print the delimited list of emails to the console window:

 

namespace ConsoleApplication1

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

 

    public class Lambdas

    {

        /// <summary>

        /// Define the Book Class

        /// </summary>

        public class Book

        {

            public string Title { get; set; }

            public string Author { get; set; }

            public double Price { get; set; }

            public string EmailAddress { get; set; }

        }

 

        public List<Book> Books { get; private set; }

 

        public Lambdas()

        {

            // Create a new list of Books

            Books = new List<Book> {

                new Book { Title = "Pro ASP.Net MVC Framework", Author = "Steven Sanderson", Price = 49.99, EmailAddress = "steve@nospam.com" },

                new Book{ Title = "Pro Silverlight 2 in C# 2008", Author = "Matthew MacDonald", Price = 49.99, EmailAddress = "Matthew@nospam.com" },

                new Book{ Title = "Pro VB 2008 and the .Net 3.5 Platform", Author = "Andrew Troelsen", Price = 59.99, EmailAddress = "Andrew@nospam.com" }

            };

        }

 

        /// <summary>

        /// Creates a semicolon (;) delimited list of email addresses

        /// </summary>

        public void ListAllEmails()

        {

            Console.WriteLine(this.Books.Select(b => b.EmailAddress).Aggregate((items, item) => items + "; " + item));

            // output= "steve@nospam.com; Matthew@nospam.com; Andrew@nospam.com"

        }

    }

}

 

The Select Method selects the EmailAddress for each Book. The Aggregate method builds a list of the items based on the lambda expression. Notice that this did not require any additional code to ensure there is no extra semi-colon at the beginning or end of the list, which is often required when using a loop to concatenate text.

 

Note: Be careful when using the Aggregate method because it is very inefficient on large numbers of strings. Consider using the String Join method instead.

 

In VB, the lambda would look like this:

 

   Console.WriteLine(Books.Select(Function(b) b.EmailAddress).Aggregate(Function(items, item) items & "; " & item))

 

You can also filter the list of email addresses. For Example, suppose you want to send an email to all the authors who sell their books for under $50, telling them that you think you can sell their next book for $59.99:

 

        /// <summary>

        /// Creates a semicolon (;) delimited list of email addresses where the price of the book is under $50

        /// </summary>

        public void ListSomeEmails()

        {

            Console.WriteLine(this.Books.Where(b => b.Price < 50).Select(b => b.EmailAddress).Aggregate((items, item) => items + ", " + item));

            // output= "steve@nospam.com, Matthew@nospam.com"

        }

 

Let's take this one step further. Suppose you wanted to create a comma separated list of values and replace the last comma with " and", so that a single item would be "item1", two items would be "item1 and item2", three items would be "item1, item2 and item3", etc.

 

        /// <summary>

        /// Creates a comma delimited list of email addresses and replaces the last comma with " and "

        /// </summary>

        public void ListEmailsAsSmartCsv()

        {

            string csv = this.Books.Select(b => b.EmailAddress).Aggregate((items, item) => items + ", " + item);

            Console.WriteLine(Regex.Replace(csv, @",\s([^,]+)$", " and $1"));

            // output= "steve@nospam.com, Matthew@nospam.com and Andrew@nospam.com"

        }

 

 


Tags:
Categories: ASP.Net | C# | VB
Posted by Williarob on Friday, February 26, 2010 9:44 AM
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Buy your next car in Europe

How would you like a free trip to Europe? If you are thinking of buying a German or Swedish car, consider taking delivery of the car at the auto maker's factory, and the savings could pay for your trip. Several auto makers not only promise hefty discounts on the price of the car, they thow other goodies into the deal, from a night's stay at a luxury hotel to roundtrip airfare for two from the U.S. The automakers - Audi, BMW, Mercedes-Benz, Porsche and Volvo - offer such perks because they have learned that European delivery programs build brand loyalty. When customers pick up their cars, they receive VIP treatment that includes escorted tours of the factories.

So how much can you save? Using a couple of Audi sedans as examples, around $1,600 on an A4 to some $3700 on an A8. The more expensive the car, the more you'll save. Here are some specifics:

  • Audi gives a five percent discount off most models' MSRP, plus one night's hotel stay and a meal at the automaker's restaurant on delivery day.
  • BMW gives seven percent off MSRP, plus two-for-one airfare on Lufthansa and a meal.
  • Mercedes-Benz gives seven percent off MSRP, two-for-one airfare on Lufthansa, one night's hotel stay and a meal.
  • Porsche offers no factory discount but it does give one night's hotel stay and lunch at the factory dining room.
  • Volvo gives eight percent off MSRP, airfare for two on Scandinavian Arilines, one night's hotel stay and a meal.

Make the trip a vacation, and with your own car, you avoid the costs of rental cars and ground transportation while you travel Europe. Each automaker provides temporary European registration, car insurance for two weeks or more, shipping to the U.S., and U.S. Customs and port clearance, all at no extra charge. You then pick up your car at the local dealer after it arrives in the U.S.

And the catch? Expect to initiate the process two to four months before your trip to Europe. And once you've finished your European excursion, expect another two months or so before you can fetch the car from your local dealer. You'll also have to time your delivery to avoid factory holidays - Europeans tend to take a lot of them.

Source: "Buying a Car in Europe", by Peter Bohr, AAA World magazine (March / April 2010)


Tags:
Posted by on Friday, February 26, 2010 8:17 AM
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Taking P90X to the next level.

First let me start by saying that I think the P90X Workout system is great. The workouts are intense, effective and fun (at least once you are finally fit enough to do them - the first time I tried the Plyometrics Jump training I barely made it through the warm up and I'll admit I still don't look forward to it). However, I believe the system works best for people who are trying to lose a little weight and add some definition, rather than those of us who are already slim and trying to add 10 lbs or more of muscle. Having said that, if you follow the program closely and watch what you eat, you certainly will gain some muscle - my arms were noticeably bigger after 90 days and my body fat had dropped from around 14% to 7%, while my body weight remained the same.

About 5 months after I started the P90X program it became apparent to me, that all the exercises relying heavily on the use dumbbells added significantly more muscle than the workouts that rely more on body weight and gravity alone (such as Chest and Back which is mostly just push ups and pull ups). Sure my chest was toned and more than a little sore after these workouts, even after 90 days, but growth was minimal. Push ups can only take you so far, especially when you only weigh 150 lbs. Since I have a gym membership, I took the standard Chest and Back, and the Chest, Shoulders, Triceps workouts and replaced most of the push ups with exercises that can be done at the gym using the machines and free weights, and immediately felt that I had taken P90X to the next level. Here is my new Chest and Back Workout:

Date:          
Warm Up, Stretch, Std Push-Ups (25) 25 25 25 25 25
Wide Front Pull-Ups          
Incline Press (Barbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Reverse Grip Chin-Ups          
Incline Press (Dumbbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Closed Grip Overhand Pull-ups          
Bench Press (Barbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Heavy Pants R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Bench Press (Dumbbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Lawnmowers R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Decline Bench Press (Dumbbell or barbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Back Flies R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Decline Push-Ups (Max Reps/25) R_______________ R_______________ R_______________ R_______________ R_______________
Elbows-out Lawnmowers R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Incline Press (Machine, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Supermans 5 5 5 5 5
Bench Press (Machine, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
CHEST & BACK          
           

Download this as an Excel Spreadsheet:

Chest & Back.xls (24.00 kb)

And here is my new Chest, Shoulders, Triceps workout:

Date:          
Warm Up, Stretch, Std Push-Ups (25) 25 25 25 25 25
In & Out Shoulder Flys R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Chair Dips R_______________ R_______________ R_______________ R_______________ R_______________
Incline Press (Barbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Deep Swimmer's Press R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Overhead Tricep Extensions R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Incline Press (Dumbbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Scarecrows R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Lying Tricep Extensions R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Bench Press (Barbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Y-Presses R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Side-Leaning Tricep Extensions R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Bench Press (Dumbbell, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Weighted Circles R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Throw the Bomb R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Decline Bench Press (Dumbbell or barbell, 2 sets) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Pour Flys (straight arms, out to sides, pour) R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Front-to-Back Tricep Extensions R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Incline Press (Machine, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
Two-Angle Shoulder Flys R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Two-Arm Tricep Kickbacks R______W_______ R______W_______ R______W_______ R______W_______ R______W_______
Bench Press (Machine, 2 sets 8-12) R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
R______W_______
CHEST, SHOULDERS & TRICEPS      
           

Chest Shoulders & Triceps.xls (24.50 kb)

I think the Back and Biceps and the Shoulder, Biceps, Triceps workouts are great as they are, just keep upping the weight whenever you can, and every once in a while (to maintain that "Muscle confusion" - and this applies to the chest workouts too), start at the bottom of your worksheet and work you way up. This will help you avoid or break through a plateau. For example, the last exercise in the Back & Biceps workout is the strip set curl, which for 90 days was always last on the list and my muscles were always pretty cooked by the time I got there. By doing the workout in reverse, this is the first exercise and your muscles are fresh, you'll be able to start with at least 5 lbs more than normal and all of the exercises on the bottom half of your workout sheet will show improvement. (After 6 months of following the worksheets in order I was struggling to improve since my body was used to the movements by now. After doing it in reverse, my body ached the next day in a way it hadn't for quite some time and 2 weeks later when I came to do it again in the right order, I was finally able to up the weights on almost all the exercises. Just be sure to mark on the sheet that you did it backwards that week.

I have been using these new worksheets for 6 weeks now, and I have gained another 3 lbs of muscle, most of it on my chest.


Categories: P90X | Fitness
Posted by Williarob on Thursday, February 25, 2010 6:44 AM
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How to update multiple tables using T-SQL

Lets say you have a database made up of many tables. All of those tables have a field called "DateCreated" which cannot be null, but at the time the tables were created, you didn't think to set a default value for the field. Now you could open each table in design mode and set the default value manually, but here is an easier way:

The syntax to set a default value looks like this:

ALTER TABLE [table-name]
ADD CONSTRAINT constraint-name DEFAULT default-value FOR column-NAME;

While quicker that opening each table in design view this still only allows you to set the default value for a single table at a time. However, we can write some simple SQL that will generate a complete SQL Script for us:

SELECT 'ALTER TABLE [' + sysobjects.NAME +
'] ADD CONSTRAINT DF_' + sysobjects.NAME + '_DateCreated DEFAULT getdate()
FOR DateCreated;' from sysobjects inner join syscolumns on
sysobjects.id = syscolumns.id
inner join systypes on
syscolumns.xtype = systypes.xtype
WHERE syscolumns.NAME = 'DateCreated'

Run that query and each row returned will contain an Alter Table statement for each table. Simply highlight all the rows returned, then copy and paste them to a new query and run it. The SysObjects table contains one row for each object (table, column, constraint, default, log, rule, stored procedure, and so on) created within a database. This means you could write a query to update the sysobjects table directly and make this even easier, but if you mess up the sysobjects table your database could be trashed so use caution if you go that route.


Categories: SQL Server
Posted by Williarob on Friday, February 19, 2010 1:35 PM
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Simplify Your Code with Lambda Expressions

Most applications retain lists of things, and a common task is to find an item in that list. The following class illustrates three ways to find an item in a generic list:

 

namespace ConsoleApplication1

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

 

    public class Lambdas

    {

        public class Book

        {

            public string Title { get; set; }

            public string Author { get; set; }

            public double Price { get; set; }

        }

 

        public List<Book> Books { get; private set; }

 

        public Lambdas()

        {

            Books = new List<Book> {

                new Book { Title = "Pro ASP.Net MVC Framework", Author = "Steven Sanderson", Price = 49.99 },

                new Book{ Title = "Pro Silverlight 2 in C# 2008", Author = "Matthew MacDonald", Price = 49.99},

                new Book{ Title = "Pro VB 2008 and the .Net 3.5 Platform", Author = "Andrew Troelsen", Price = 59.99 }

            };

        }

 

        /// <summary>

        /// Returns a book using a traditional loop

        /// </summary>

        private Book FindUsingTraditionalLoop(string title)

        {

            Book foundBook = null;

 

            foreach (var b in this.Books)

            {

                if (b.Title == title)

                {

                    foundBook = b;

                    break;

                }

            }

 

            return foundBook;

        }

 

        /// <summary>

        /// Returns the book using a Linq expression

        /// </summary>

        private Book FindUsingLinq(string title)

        {

            var query = from b in this.Books

                        where b.Title == title

                        select b;

 

            return query.Count() > 0 ? query.ToList()[0] : null;

        }

 

        /// <summary>

        /// Returns the book using a Lambda expression

        /// </summary>

        private Book FindUsingLambda(string title)

        {

            return this.Books.FirstOrDefault(b => b.Title == title);

        }

 

        public void Test()

        {

            Console.WriteLine("Found: {0}", this.FindUsingTraditionalLoop("Pro Silverlight 2 in C# 2008").Author);

            Console.WriteLine("Found: {0}", this.FindUsingLinq("Pro Silverlight 2 in C# 2008").Author);

            Console.WriteLine("Found: {0}", this.FindUsingLambda("Pro Silverlight 2 in C# 2008").Author);

        }

    }

}

As these examples show, you can save time reading and writing your code by using Lambda expressions to find items in a list.

For VB programmers, the syntax of the Lambda expression looks like this:

return Me.Books.FirstOrDefault(Function(b) b.Title = title)


Categories: ASP.Net | C# | VB
Posted by Williarob on Wednesday, January 06, 2010 8:10 AM
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