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Posted 31 Jan 2012

Render Exceptions in an Entity Framework application

, 8 Feb 2012
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Extension Method for exceptions that give a useful text even on Entity Framework Exceptions

Did you know that exceptions thrown by Entity Framework contain useful information? They are buried in some properties of an inner exception. Here's the code that makes them visible:

public static class Extensions
    /// <summary>
    /// Renders an exception with messages and stack traces
    /// </summary>
    /// <param name="ex">The exception to render</param>    
    /// <param name="noTrace">Whether trace information should be omitted</param>
    /// <returns>A string containing messages and stack traces</returns>
    public static string Render(this Exception ex, bool noTrace = false)
        var s = new StringBuilder("\n");
        int i = 0;
            s.AppendFormat("{0:#\\. inner E;;E}xception ({1}):\n   {2}\n", 
                ex.Message.Replace("\n", "\n   "));
            if (ex is UpdateException)
                foreach (var stateEntry in ((UpdateException)ex).StateEntries)
                    var entity = stateEntry.Entity ?? new object();
                    s.AppendFormat("     {0} {1}: {2}\n", stateEntry.State, entity.GetType().Name, entity);
                    var values =
                        stateEntry.State == EntityState.Deleted
                            ? stateEntry.OriginalValues
                            : stateEntry.CurrentValues;
                    for (int j = 0; j < values.FieldCount; j++)
                        var currentValue = values[j];
                        var originalValue =
                            stateEntry.State == EntityState.Added
                                ? currentValue
                                : stateEntry.OriginalValues[j];
                        s.AppendFormat(originalValue.Equals(currentValue) ? "      {0}: <{1}>\n" : "      {0}: <{1}>→<{2}\n",
                                       values.GetName(j), originalValue, currentValue);
            s.AppendFormat(noTrace ? "\n" : "Trace:\n{0}\n", ex.StackTrace);
            ex = ex.InnerException;
        while (ex != null);
        return s.ToString();


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


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Comments and Discussions

GeneralThanks for this snippet. How to properly use them? Please wr... Pin
evlntnt16-Feb-12 2:16
memberevlntnt16-Feb-12 2:16 

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Article Copyright 2012 by Harry von Borstel
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