How to set up Automapper in ASP.NET Core

I figured it out! Here’s the details:

1. Add the main AutoMapper Package to your solution via NuGet.

2. Add the AutoMapper Dependency Injection Package to your solution via NuGet.

3. Create a new class for a mapping profile. (I made a class in the main solution directory called MappingProfile.cs and add the following code.) I’ll use a User and UserDto object as an example.

    public class MappingProfile : Profile {
        public MappingProfile() {
            // Add as many of these lines as you need to map your objects
            CreateMap<User, UserDto>();
            CreateMap<UserDto, User>();
        }
    }
   

4. Then add the AutoMapperConfiguration in the Startup.cs as shown below:

    public void ConfigureServices(IServiceCollection services) {
        // .... Ignore code before this
   
       // Auto Mapper Configurations
        var mapperConfig = new MapperConfiguration(mc =>
        {
            mc.AddProfile(new MappingProfile());
        });
   
        IMapper mapper = mapperConfig.CreateMapper();
        services.AddSingleton(mapper);
   
        services.AddMvc();
   
    }
   

5. To invoke the mapped object in code, do something like the following:

    public class UserController : Controller {
   
        // Create a field to store the mapper object
        private readonly IMapper _mapper;
   
        // Assign the object in the constructor for dependency injection
        public UserController(IMapper mapper) {
            _mapper = mapper;
        }
   
        public async Task<IActionResult> Edit(string id) {
   
            // Instantiate source object
            // (Get it from the database or whatever your code calls for)
            var user = await _context.Users
                .SingleOrDefaultAsync(u => u.Id == id);
   
            // Instantiate the mapped data transfer object
            // using the mapper you stored in the private field.
            // The type of the source object is the first type argument
            // and the type of the destination is the second.
            // Pass the source object you just instantiated above
            // as the argument to the _mapper.Map<>() method.
            var model = _mapper.Map<UserDto>(user);
   
            // .... Do whatever you want after that!
        }
    }