AutoMapper using the wrong constructor
automapper, automapper-2, c#
Solution
You just need to add explicit cast to
Func<ResolutionContext, TypeOne>
Here is the code:
Mapper.CreateMap<TypeOneDto, TypeOne>().ConstructUsing(
(Func<ResolutionContext, TypeOne>) (r => new TypeOne()));
Current version of AutoMapper works as described below:
Sorts destination type constructors by parameter count
destTypeInfo.GetConstructors().OrderByDescending(ci => ci.GetParameters().Length);
Takes first constructor which parameters match source properties (without any check for null value). In your case it is constructor with two parameters.
Problem
Today I upgraded a fully functioning application using AutoMapper v1.1 to now use AutoMapper v2.1 and I am coming across some issues that I never encountered using the previous version. Here is an example of my code mapping back from Dto to Domain object ``` public class TypeOne { public TypeOne() { } public TypeOne(TypeTwo two) { //throw ex if two is null } public TypeOne(TypeTwo two, TypeThree three) { //throw ex if two or three are null } public TypeTwo Two {get; private set;} public TypeThree Three {get; private set;} } public class TypeOneDto { public TypeOneDto() { } public TypeTwoDto Two {get; set;} public TypeThreeDto Three {get; set;} } ``` ... ``` Mapper.CreateMap<TypeThreeDto, TypeThree>(); Mapper.CreateMap<TypeTwoDto, TypeTwo>(); Mapper.CreateMap<TypeOneDto, TypeOne>(); var typeOne = Mapper.Map<TypeOne>(typeOneDto); ``` However the first problem I encountered with v2.1 was that AutoMapper was trying to use the constructor with 2 args when one of the args was null and should be using the 1 arg constructor. I then tried to use ``` Mapper.CreateMap<TypeOneDto, TypeOne>().ConstructUsing(x => new TypeOne()); ``` But I kept getting an 'Ambiguous Invocation' error that I couldn't resolve. I then tried ``` Mapper.CreateMap<TypeOneDto, TypeOne>().ConvertUsing(x => new TypeOne()); ``` and that did successfully create the TypeOne object using the parameterless constructor but then it failed to set the private setter properties. I have looked for help on the AutoMapper website and downloaded the source code to have a good look but didn't get far with the little documentation about and there were not many unit tests for ConstructUsing. Is there anything obvious I am missing that I should change with v2.1? I am surprised that it has changed so much from v1.1.