AutoMapper.Mapper.CreateMap()' is obs

问题:

I have to classes Like

class A
{
 public int id {get; set;}
}

class B
{
 public C c {get; set;}
}

class C
{
 public int id {get; set;}
 public string Name {get; set;}
}

My requirement is to map id of class A to id of class C. Now what I was doing till now was: Mapper.CreateMap().ForMember(des => des.C.Id, src => src.MapFrom(x => x.id));

and it was working fine.

Now seems like Auto mapper has changed their implementation. and I am getting warning as below:

AutoMapper.Mapper.CreateMap()' is obsolete: 'Dynamically creating maps will be removed in version 5.0. Use a MapperConfiguration instance and store statically as needed, or Mapper.Initialize. Use CreateMapper to create a mapper instance.

I need to map some properties of classes which has different name and structure. Any help on this.

回答1:

Previously

  Mapper.CreateMap<Src, Dest>()
 .ForMember(d => d.UserName, opt => opt.MapFrom(/* ????? */));

The problem here is mapping definitions are static, defined once and reused throughout the lifetime of the application. Before 3.3, you would need to re-define the mapping on every request, with the hard-coded value. And since the mapping configuration is created in a separate location than our mapping execution, we need some way to introduce a runtime parameter in our configuration, then supply it during execution.

This is accomplished in two parts: the mapping definition where we create a runtime parameter, then at execution time when we supply it. To create the mapping definition with a runtime parameter, we “fake” a closure that includes a named local variable:

Mapper.Initialize(cfg => {

string userName = null;
cfg.CreateMap<Source, Dest>()
    .ForMember(d => d.UserName, 
        opt => opt.MapFrom(src => userName)
    );
});

For more information see this

For one or more classes

 cfg.CreateMissingTypeMaps = true;
 cfg.CreateMap<Source, Dest>()
    .ForMember(d => d.UserName, 
        opt => opt.MapFrom(src => userName)
    );

 cfg.CreateMap<AbcEditViewModel, Abc>();
 cfg.CreateMap<Abc, AbcEditViewModel>();
});

In mapping class

  IMapper mapper = config.CreateMapper();
  var source = new AbcEditViewModel();
  var dest = mapper.Map<AbcEditViewModel, Abct>(source);

回答2:

Finally I found the resolution. I was doing: Mapper.Initialize{ Mapping field from source to destination } in the App_start and adding this file to the global.asax--> Application_Start() --> GlobalConfiguration.

I need to add one more line inside my Mapper.Initialize which is cfg.CreateMissingTypeMaps = true;

Now this code will work for explicit mapping where two classes don't have the same structure and names of properties.

Apart from this, if we need to map properties of two class with the same structure the code Mapper.map(source, destination) will also work, which was not working earlier.

Let me know if someone is having difficulty with the solution. Thanks all for the above reply.

回答3:

Another way that seems a bit cleaner is to make a MappingProfile class which inherits from the Profile class of AutoMapper

public class MappingProfile:Profile
{
    public MappingProfile()
    {
        CreateMap<Source1, Destination1>();
        CreateMap<Source2, Destination2>();
        ...
    }
}

Then you initialize the mapping with Mapper.Initialize(c => c.AddProfile<MappingProfile>()); in your startup code

That will allow you to use the mapping anywhere by calling

destination1Collection = source1Collection.Select(Mapper.Map<Source1, Destination1>);