Class Mapping Error: 'T' must be a non-abstract type with a public parameterless constructor

Question

While mapping class i am getting error \'T\' must be a non-abstract type with a public parameterless constructor in order to use it as parameter \'T\' in the generic type or

Answer 1

The constraints must apply to every type in the chain; hence you need:

public abstract class SqlReaderBase : ConnectionProvider where T : new()

Without this, you can't satisfy the constraint for T in:

protected abstract MapperBase GetMapper();

or

MapperBase mapper = GetMapper();

since MapperBase<> is only usable when T has : new()