Erroneous or unnecessary restriction on specific object mappers

[nivedano]

Is there an existing issue for this?

• I have searched the existing issues

Description

Currently, DefaultObjectMapper.TryToMapCollection searches only public methods of a specific object mapper via GetMethods() with no args:

return specificMapper
      .GetType()
      .GetMethods()
      .First(x =>
          x.Name == nameof(IObjectMapper<object, object>.Map) &&
          x.GetParameters().Length == (destination == null ? 1 : 2)
      );

abp/framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/DefaultObjectMapper.cs

Line 147 in f96b918

.GetMethods()

This call only returns public methods, omitting explicit interface realizations. Such a restriction leads to rather rather inefficient designs, when you need to implement a bunch of related mappings with the same source type, but IObjectMapper<TSource, TDestination>.Map(TSource) definitions will collide on the mapper type if you try to implement the interfaces in a regular way.

Also, .First method, when no map found throws an unspecific exception, which tells nothing essential about what is wrong.

Reproduction Steps

No response

Expected behavior

1. Change the line from .GetMethods() to .GetMethods(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Public) to allow explicit interface implementations for mappers. Plus parameter matching logic.
2. Change .First(...) for more descriptive error explanation, like this .FirstOrDefault(...) ?? throw new InvaildOperationException($"No specific mapper method found on type {mapperType.FullName}") or better

Actual behavior

No response

Regression?

No response

Known Workarounds

No response

Version

8.2.2

User Interface

Common (Default)

Database Provider

EF Core (Default)

Tiered or separate authentication server

None (Default)

Operation System

Windows (Default)

Other information

No response

[maliming]

Is this a problem? How to reproduce?

[nivedano]

Is this a problem? How to reproduce?

Yes, this is a design problem.

class ADto {}
class AWithDetailsDto {}

class ABMapper: 
    // You can't have these both implemented via public methods, Map() methods collide.
    // You've got to spawn the classes. It got the more complicated, the more complex logic is associated with the mappings
    IObjectMapper<A, ADto>, 
    IObjectMapper<A, AWithDetaildDto>,
    ITransientDependency
{
    // you can compile this, but it won't work with the current DefaultObjectMapper.TryToMapCollections
    ADto IObjectMapper<A, ADto>.Map(A source) => ...;
    AWithDetailsDto IObjectMapper<A, AWithDetailsDto>.Map(A source) => ...;
}