Question

This question is in relation to another question I have: Using iBATIS.NET with generic custom collection interfaces and Unity

The problem seems to be that iBATIS.NET will only populate a custom collection (i.e. QueryForObject(‘Select_Foo’) which has a custom collection of Bars) if it is a concrete instance of custom collection not an interface. Does anyone know if this is a limitation of iBATIS.NET or if there is a way of doing this?

Thanks,

Paul

Answer 1

If I understood you right then you’d like to get full control over the way how iBatis maps to some object.

You can do this with the ITypeHandlerCallback. Have a look for a full description in the PDF documentation in section ‘3.5.5. Custom Type Handlers’.

I have done something similar with DataTables. Your implementation might look similar to this:

class DataTableBuilder : ITypeHandlerCallback {     public object GetResult(IResultGetter getter)     {         IDataReader reader = getter.DataReader;          // (A) define whatever type you want to          // (B) read rows from DataReader and populate your type from (A)         while (reader.Read())         {             // iterate over the columns of the current row             for (int i = 0; i < reader.FieldCount; i++)             {                // populate your type from (A)             }                             }         return ...;   // return your type from (A)     }      // implement the other members of ITypeHandlerCallback     // the implementation below actually worked for me     public object NullValue { get { return null; } }     public void SetParameter(IParameterSetter setter, object parameter) { }     public object ValueOf(string s) { return s; } } 

A last note: iBatis is fine for building data transfer objects (DTOs). If you try something like above, you might already moving toward a business object approach. This might get painful with iBatis. Currently (well … for a few months already, due to lack of time) I am evaluating NHibernate as an alternative. I think that NHibernate is handling business object approaches much more smoothly than iBatis does.