Automapper and request specific resources - unity-container

Question

I'm considering automapper for an asp mvc intranet app I am writing. My controllers are currently created using Unity dependency injection, where each container gets dependencies unique to the request.
I need to know if automapper can be made to use a request specific resource ICountryRepository to look up an object, like so....
domainObject.Country = CountryRepository.Load(viewModelObject.CountryCode);

Answer 1

Couple of options here. One is to do a custom resolver:
.ForMember(dest => dest.Country, opt => opt.ResolveUsing<CountryCodeResolver>())
Then your resolver would be (assuming CountryCode is a string. Could be a string, whatever):
public class CountryCodeResolver : ValueResolver<string, Country> {
private readonly ICountryRepository _repository;
public CountryCodeResolver(ICountryRepository repository) {
_repository = repository;
}
protected override Country ResolveCore(string source) {
return _repository.Load(source);
}
}
Finally, you'll need to hook in Unity to AutoMapper:
Mapper.Initialize(cfg => {
cfg.ConstructServicesUsing(type => myUnityContainer.Resolve(type));
// Other AutoMapper configuration here...
});
Where "myUnityContainer" is your configured Unity container. A custom resolver defines a mapping between one member and another. We often define a global type converter for all string -> Country mappings, so that I don't need to configure every single member. It looks like this:
Mapper.Initialize(cfg => {
cfg.ConstructServicesUsing(type => myUnityContainer.Resolve(type));
cfg.CreateMap<string, Country>().ConvertUsing<StringToCountryConverter>();
// Other AutoMapper configuration here...
});
Then the converter is:
public class StringToCountryConverter : TypeConverter<string, Country> {
private readonly ICountryRepository _repository;
public CountryCodeResolver(ICountryRepository repository) {
_repository = repository;
}
protected override Country ConvertCore(string source) {
return _repository.Load(source);
}
}
In a custom type converter, you wouldn't need to do any member-specific mapping. Any time AutoMapper sees a string -> Country conversion, it uses the above type converter.