TypeHandler should be supported for enum

[ShamsulAmry]

In the database, I'm storing single character status codes, and an enum to match the status codes. However, since the status codes are not integer and not direct string match against the enum I created, I implemented a TypeHandler to do custom deserialization from the status code to the enum. Then I found out Dapper will not call the TypeHandler for enum types, so here's the fix.

Basically I moved the TypeHandler cache check to the beginning of the block even before enum value processing because I believe user-defined TypeHandlers should come first before anything else, no?

[vdaron]

Related to #259

[ShamsulAmry]

Related to #258 too

[drusellers]

👍 want

[NickCraver]

I believe this is now properly handled, see current code here:

if (hasTypeHandler)
{
#pragma warning disable 618
    il.EmitCall(OpCodes.Call, typeof(TypeHandlerCache<>).MakeGenericType(unboxType).GetMethod("Parse"), null); // stack is now [target][target][typed-value]
#pragma warning restore 618
}
else
{
    il.Emit(OpCodes.Unbox_Any, unboxType); // stack is now [target][target][typed-value]
}

If I'm missing something though, comment here and I'm happy to open the issue back up.

[vdaron]

Hi, current master branch doesn't work for me. The LookupDbType will not return the ITypeHandler if one is defined for an Enum and the deserializer IL generated code seems to ignore ITypeHandler for Enums.

This sample ITypeHandler is ignored for example :

public enum TestEnum
{
   One,Two,Three
}

public class EnumAsIntTypeHandler<T> : ITypeHandler
{
   public void SetValue(IDbDataParameter parameter, object value)
   {
      parameter.DbType = DbType.Int32;
      parameter.Value = (int)value;
   }
   public object Parse(Type destinationType, object value)
   {
      return (T)value;
   }
}

...
SqlMapper.AddTypeHandler(typeof(TestEnum), new EnumAsIntTypeHandler<TestEnum>());
...

Thanks for feedback @NickCraver !

Edit:I'm perfectly aware that my ITypeHandler sample is the default behavior for Enums :-)

[floyd-may]

+1, same behavior experienced as @vdaron. Need to be able to map letter codes to enums and back.