I'm looking for a way to change the default implementation of ITypeMap used by Dapper.
The database I am working on uses underscores in all the column names. For example "COLUMN_NAME". I don't want to have my POCO classes use property names with underscores, I'd rather use C# conventions for naming properties on my POCO classes. I also, dont want to have to write long select lists of "COLUMN_NAME AS ColumnName", or even give up the ability to do "SELECT * FROM ..".
I've found that Dapper allows me to write my own ITypeMap, which I have done and it works great! For my case I can write one mapper that will work for any select statement -- it just simply maps column names to property names with the underscores removed. However, because I have my own implementation of ITypeMap I must make a call to SqlMapper.SetTypeMap() at least one time for each POCO type. One of the things I like about Dapper is that there are no setup calls required at all when you use the default mapper. I am desperately trying to hold on to that experience as much as possible, while using the custom ITypeMap.
So instead of the elegant:
connection.Query<Animal>("select..");
I have:
SqlMapper.SetTypeMap(typeof(Animal), new TypeMap<Animal>());
connection.Query<Animal>("select..");
There is even more code when you start keeping track of which types have already been registered with SetTypeMap().
The best solution I have come up with so far is to wrap all the overrides of SqlMapper.Query(). In the wrapped methods I can check and call SetTypeMap() before calling SqlMapper.Query().
Something like this:
public static class DapperWrapper
{
private static List<Type> _knownTypes = new List<Type>();
public static IEnumerable<T> Query2<T>(this IDbConnection cnn, string sql, ...);
{
Setup<T>();
return cnn.Query<T>(sql, ...);
}
private static void Setup<T>()
{
Type type = typeof(T);
if (!_knownTypes.Contains(type))
{
SqlMapper.SetTypeMap(type, new TypeMap<T>());
_knownTypes.Add(type);
}
}
}
This gets me back to where I want to be:
connection.Query2<Animal>("select..");
Is there a better way of doing this? It seems like DapperExtensions has something like this in the AutoMapper, but it is not clear to me if that works with SqlMapper.Query().
