Sending the LINQ To SQL log to the debugger output window

15 March 2007 Kris-Vandermotten LINQ

I was playing with LINQ To SQL (again) this evening, and I thought: why can't I see the generated SQL statements in my debugger output window?

The DataContext.Log property is a great help to learn writing LINQ To SQL queries. All you need to do is assign a TextWriter to it, and you get to see al the SQL statements generated by the data context. But where do you send them to? Console.Out is an option, but you probably don't want that in a release build. Furthermore, it doesn't quite work for Windows services or ASP.NET applications. That's why I wrote DebuggerWriter, an implementation of TextWriter that writes to the debugger log.

All you need to do to use it is:

MyDataContext db = new MyDataContext(); 
 
db.Log = new DebuggerWriter();


Here's the code:

using System; 
using System.Diagnostics; 
using System.Globalization; 
using System.IO; 
using System.Text; 
 
namespace Vandermotten.Diagnostics { 
    /// <summary> 
    /// Implements a <see cref="TextWriter"/> for writing information to the debugger log. 
    /// </summary> 
    /// <seealso cref="Debugger.Log"/> 
    public class DebuggerWriter : TextWriter 
    { 
        private bool isOpen; 
        private static UnicodeEncoding encoding; 
        private readonly int level; 
        private readonly string category; 
 
        /// <summary> 
        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class. 
        /// </summary> 
        public DebuggerWriter() 
            : this(0, Debugger.DefaultCategory) 
        { 
        } 
 
        /// <summary> 
        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class with the specified level and category. 
        /// </summary> 
        /// <param name="level">A description of the importance of the messages.</param> 
        /// <param name="category">The category of the messages.</param> 
        public DebuggerWriter(int level, string category) 
            : this(level, category, CultureInfo.CurrentCulture) 
        { 
        } 
 
        /// <summary> 
        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class with the specified level, category and format provider. 
        /// </summary> 
        /// <param name="level">A description of the importance of the messages.</param> 
        /// <param name="category">The category of the messages.</param> 
        /// <param name="formatProvider">An <see cref="IFormatProvider"/> object that controls formatting.</param> 
        public DebuggerWriter(int level, string category, IFormatProvider formatProvider) 
            : base(formatProvider) 
        { 
            this.level = level; 
            this.category = category; 
            this.isOpen = true; 
        } 
 
        protected override void Dispose(bool disposing) 
        { 
            isOpen = false; 
            base.Dispose(disposing); 
        } 
 
        public override void Write(char value) 
        { 
            if (!isOpen) 
            { 
                throw new ObjectDisposedException(null); 
            } 
            Debugger.Log(level, category, value.ToString()); 
        } 
 
        public override void Write(string value) 
        { 
            if (!isOpen) 
            { 
                throw new ObjectDisposedException(null); 
            } 
 
            if (value != null) 
            { 
                Debugger.Log(level, category, value); 
            } 
        } 
 
        public override void Write(char[] buffer, int index, int count) 
        { 
            if (!isOpen) 
            { 
                throw new ObjectDisposedException(null); 
            } 
 
            if (buffer == null || index < 0 || count < 0 || buffer.Length - index < count) 
            { 
                base.Write(buffer, index, count); // delegate throw exception to base class 
            } 
 
            Debugger.Log(level, category, new string(buffer, index, count)); 
        } 
 
        public override Encoding Encoding 
        { 
            get 
            { 
                if (encoding == null) 
                { 
                    encoding = new UnicodeEncoding(false, false); 
                } 
 
                return encoding; 
            } 
        } 
 
        public int Level 
        { 
            get { return level; } 
        } 
 
        public string Category 
        { 
            get { return category; } 
        } 
    } 
}


Enjoy!

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