C# - IDataReader to Object mapping using generics

Question

How can I map a DataReader object into a class object by using generics?

For example I need to do the following:

public class Mapper
    {
          


        

Answer 1

I don't think you'll be able to get around defining the relationship between fields in some form. Take a look at this article and pay particular attention to how the mapping is defined, it may work for you.

http://www.c-sharpcorner.com/UploadFile/rmcochran/elegant_dal05212006130957PM/elegant_dal.aspx

Answer 2

I use ValueInjecter for this

I'm doing like this:

 while (dr.Read())
  {
      var o = new User();
      o.InjectFrom<DataReaderInjection>(dr);
      yield return o;
  }

you gonna need this ValueInjection for this to work:

public class DataReaderInjection : KnownSourceValueInjection<IDataReader>
    {
        protected override void Inject(IDataReader source, object target, PropertyDescriptorCollection targetProps)
        {
            for (var i = 0; i < source.FieldCount; i++)
            {
                var activeTarget = targetProps.GetByName(source.GetName(i), true);
                if (activeTarget == null) continue;

                var value = source.GetValue(i);
                if (value == DBNull.Value) continue;

                activeTarget.SetValue(target, value);
            }
        }
    }

Answer 3

What about using Fluent Ado.net ?

Answer 4

The easiest way I can think of offhand would be to supply a Func<T,T> delegate for converting each column and constructing your book.

Alternatively, if you followed some conventions, you could potentially handle this via reflection. For example, if each column mapped to a property in the resulting object using the same name, and you restricted T in your Mapper to providing a constructable T, you could use reflection to set the value of each property to the value in the corresponding column.

Answer 5

Well, i don't know if it fits here, but you could be using the yield keyword

public static IEnumerable<T> MapObject(IDataReader dr, Func<IDataReader, T> convertFunction)
        {
            while (dr.Read())
            {
                yield return convertFunction(dr);
            }
        }

Answer 6

I would recommend that you'd use AutoMapper for this.