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POCO Entities Through RIA Services

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10 Dec 2010CPOL11 min read 49K   1.1K   29  
This article demonstrates how to generate plain old class objects (POCO) from the Entity Framework v4 (EF4) and use them through RIA Services in SilverLight version 4.
namespace BusinessApp
{
    using System;
    using System.Diagnostics;
    using System.Windows;
    using System.Windows.Controls;
    using System.Net;

    /// <summary>
    /// Controls when a stack trace should be displayed in the ErrorWindow.
    /// Defaults to <see cref="OnlyWhenDebuggingOrRunningLocally"/>
    /// </summary>
    public enum StackTracePolicy
    {
        /// <summary>
        ///   Stack trace is shown when running with a debugger attached or when running the app on the local machine.
        ///   Use this to get additional debug information you don't want the end users to see.
        /// </summary>
        OnlyWhenDebuggingOrRunningLocally,

        /// <summary>
        /// Always show the stack trace, even if debugging
        /// </summary>
        Always,

        /// <summary>
        /// Never show the stack trace, even when debugging
        /// </summary>
        Never
    }

    /// <summary>
    /// <see cref="ChildWindow"/> class that displays errors to the user.
    /// </summary>
    public partial class ErrorWindow : ChildWindow
    {
        /// <summary>
        /// Creates a new <see cref="ErrorWindow"/> instance.
        /// </summary>
        /// <param name="message">The error message to display.</param>
        /// <param name="errorDetails">Extra information about the error.</param>
        protected ErrorWindow(string message, string errorDetails)
        {
            InitializeComponent();
            IntroductoryText.Text = message;
            ErrorTextBox.Text = errorDetails;
        }

        #region Factory Shortcut Methods
        /// <summary>
        /// Creates a new Error Window given an error message.
        /// Current stack trace will be displayed if app is running under debug or on the local machine.
        /// </summary>
        /// <param name="message">The message to display.</param>
        public static void CreateNew(string message)
        {
            CreateNew(message, StackTracePolicy.OnlyWhenDebuggingOrRunningLocally);
        }

        /// <summary>
        /// Creates a new Error Window given an exception.
        /// Current stack trace will be displayed if app is running under debug or on the local machine.
        /// 
        /// The exception is converted onto a message using <see cref="ConvertExceptionToMessage"/>.
        /// </summary>
        /// <param name="exception">The exception to display.</param>
        public static void CreateNew(Exception exception)
        {
            CreateNew(exception, StackTracePolicy.OnlyWhenDebuggingOrRunningLocally);
        }

        /// <summary>
        /// Creates a new Error Window given an exception.
        /// The exception is converted into a message using <see cref="ConvertExceptionToMessage"/>.
        /// </summary>    
        /// <param name="exception">The exception to display.</param>
        /// <param name="policy">When to display the stack trace, see <see cref="StackTracePolicy"/>.</param>
        public static void CreateNew(Exception exception, StackTracePolicy policy)
        {
            if (exception == null)
            {
                throw new ArgumentNullException("exception");
            }

            string fullStackTrace = exception.StackTrace;

            // Account for nested exceptions
            Exception innerException = exception.InnerException;
            while (innerException != null)
            {
                fullStackTrace += "\nCaused by: " + exception.Message + "\n\n" + exception.StackTrace;
                innerException = innerException.InnerException;
            }

            CreateNew(ConvertExceptionToMessage(exception), fullStackTrace, policy);
        }

        /// <summary>
        /// Creates a new Error Window given an error message.
        /// </summary>   
        /// <param name="message">The message to display.</param>
        /// <param name="policy">When to display the stack trace, see <see cref="StackTracePolicy"/>.</param>
        public static void CreateNew(string message, StackTracePolicy policy)
        {
            CreateNew(message, new StackTrace().ToString(), policy);
        }
        #endregion

        #region Factory Methods
        /// <summary>
        /// All other factory methods will result in a call to this one.
        /// </summary>
        /// 
        /// <param name="message">The message to display</param>
        /// <param name="stackTrace">The associated stack trace</param>
        /// <param name="policy">The situations in which the stack trace should be appended to the message</param>
        private static void CreateNew(string message, string stackTrace, StackTracePolicy policy)
        {
            string errorDetails = string.Empty;

            if (policy == StackTracePolicy.Always ||
                policy == StackTracePolicy.OnlyWhenDebuggingOrRunningLocally && IsRunningUnderDebugOrLocalhost)
            {
                errorDetails = stackTrace ?? string.Empty;
            }

            ErrorWindow window = new ErrorWindow(message, errorDetails);
            window.Show();
        }
        #endregion

        #region Factory Helpers
        /// <summary>
        /// Returns whether running with a debugger attached or with the server hosted on localhost.
        /// </summary>
        private static bool IsRunningUnderDebugOrLocalhost
        {
            get
            {
                if (Debugger.IsAttached)
                {
                    return true;
                }
                else
                {
                    string hostUrl = Application.Current.Host.Source.Host;
                    return hostUrl.Contains("::1") || hostUrl.Contains("localhost") || hostUrl.Contains("127.0.0.1");
                }
            }
        }

        /// <summary>
        /// Creates a user-friendly message given an Exception. 
        /// Currently this method returns the Exception.Message value. 
        /// You can modify this method to treat certain Exception classes differently.
        /// </summary>
        /// <param name="e">The exception to convert.</param>
        private static string ConvertExceptionToMessage(Exception e)
        {
            return e.Message;
        }
        #endregion

        private void OKButton_Click(object sender, RoutedEventArgs e)
        {
            this.DialogResult = true;
        }
    }
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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