AutoMapper 3.1.1 and Entity Framework 6.1 Proxy objects

问题

I realized this has been asked already, but the solutions I've read don't seem to make a difference so far. I'm using Entity Framework 6.1 and AutoMapper 3.1.1. Taking the following objects: Company and CompanyListItem; I try this:

Mapper.Configure<Company, CompanyListItem>();

Well, when I try to do the actual mapping it crashed and burned with an exception that there's no mappings defined. I know this is caused because of the proxy objects created by Entity Framework. One solutions I've seen so far is to call an overloaded version of the Map method:

IQueryable<Company> companies = CompaniesService.FindCompanies();

Mapper.Map(companies, typeof(Company[]), typeof(CompanyListItem[]));

And it still doesn't work and yells at me.

I've also read other posts that this has been fixed as of 2.2.1? Is this different or did it regress? I'd appreciate suggestions.

回答1:

You are using Automapper incorrectly, you need to use the QueryableExtensions namespace, so your code should be

IQueryable<Company> companies = CompaniesService.FindCompanies();

CompanyListItem[] results = companies.Project().To<CompanyListItem>().ToArray();

Also if you where going to do it the other way you still had Mapper.Map wrong, it should have been

IQueryable<Company> companies = CompaniesService.FindCompanies();

CompanyListItem[] result = Mapper.Map<IEnumerable<Company>,CompanyListItem[]>(companies);

but I still recommend doing the .Project().To<T>() method as it will perform the mapping server side instead of client side so you potentially have less data that needs to be sent over the wire.

来源：https://stackoverflow.com/questions/22723133/automapper-3-1-1-and-entity-framework-6-1-proxy-objects