title: TypeHandler<T> doesn't seem to be called
body: <h1>The short version</h1>
  
  <p><code>SqlMapper.Query&lt;T&gt;</code> seems to ignore my registered <code>TypeHandler&lt;T&gt;</code></p>
  
  <h1>The long version</h1>
  
  <p>Here's a simple query:</p>
  
  <pre><code>SELECT 'Foo' AS CategoryName, 200 AS CategoryRating
  </code></pre>
  
  <p>...and here's two POCOs:</p>
  
  <pre><code>public class RatingValue
  {
      public Int32 Value { get; set; }
      // ... some other properties etc ...
  }
  
  public class MyResult
  {
      public String CategoryName { get; set; }
      public RatingValue CategoryRating { get; set; }
  }
  </code></pre>
  
  <p>I've created a new <code>TypeHandler</code> implementation which <em>should</em> turn that CategoryRating <code>Int32</code> into a <code>RatingValue</code> object:</p>
  
  <pre><code>public class RatingValueHandler: SqlMapper.TypeHandler&lt;RatingValue&gt;
  {
      public override RatingValue Parse(object value)
      {
          if (value is Int32)
              return new RatingValue() { Value = (Int32)value };
  
          throw new FormatException("Invalid conversion to RatingValue");
      }
  
      public override void SetValue(System.Data.IDbDataParameter parameter, RatingValue value)
      {
          // ... null, range checks etc ...
          parameter.DbType = System.Data.DbType.Int32;
          parameter.Value = Int32.Parse(value.Value);
      }
  }
  </code></pre>
  
  <p>Now, before running my query I'm adding my new handler like this:</p>
  
  <pre><code>SqlMapper.AddTypeHandler&lt;RatingValue&gt;(new RatingValueHandler());
  </code></pre>
  
  <p>However, when I run this:</p>
  
  <pre><code>c.Query&lt;MyResult&gt;("SELECT 'Foo' AS CategoryName, 200 AS CategoryRating");
  </code></pre>
  
  <p>I get an exception from Dapper - it couldn't parse the results in column 1.
  I <em>expected</em> Dapper to fire my custom type handler!</p>
  
  <p><strong>I think I'm missing something very, very obvious. Please tell me how silly I am!</strong></p>