Nsryjdtyk

theutz' answer here is very good, I just want to add this:

If you let your mapping profile inherit from MapperConfigurationExpression instead of Profile, you can very simply add a test to verify your mapping setup, which is always handy:

[Fact]

public void MappingProfile_VerifyMappings()

{

    var mappingProfile = new MappingProfile();



    var config = new MapperConfiguration(mappingProfile);

    var mapper = new Mapper(config);



    (mapper as IMapper).ConfigurationProvider.AssertConfigurationIsValid();

}

I want to extend @theutz's answers - namely this line :

// services.AddAutoMapper(typeof(Startup));  // <-- newer automapper version uses this signature.

There is a bug (probably) in AutoMapper.Extensions.Microsoft.DependencyInjection version 3.2.0. (I'm using .NET Core 2.0)

This is tackled in this GitHub issue. If your classes inheriting AutoMapper's Profile class exist outside of assembly where you Startup class is they will probably not be registered if your AutoMapper injection looks like this:

services.AddAutoMapper();

unless you explicitly specify which assemblies to search AutoMapper profiles for.

It can be done like this in your Startup.ConfigureServices:

services.AddAutoMapper(<assembies> or <type_in_assemblies>);

where "assemblies" and "type_in_assemblies" point to the assembly where Profile classes in your application are specified. E.g:

services.AddAutoMapper(typeof(ProfileInOtherAssembly), typeof(ProfileInYetAnotherAssembly));

I suppose (and I put emphasis on this word) that due to following implementaion of parameterless overaload (source code from GitHub) :

public static IServiceCollection AddAutoMapper(this IServiceCollection services)

{

     return services.AddAutoMapper(null, AppDomain.CurrentDomain.GetAssemblies());

}

we rely on CLR having already JITed assembly containing AutoMapper profiles which might be or might not be true as they are only jitted when needed (more deatils in this StackOverflow question).

Step To Use AutoMapper with ASP.NET Core.

Step 1. Installing AutoMapper.Extensions.Microsoft.DependencyInjection from NuGet Package.

Step 2. Create a Folder in Solution to keep Mappings with Name "Mappings".

Step 3. After adding Mapping folder we have added a class with Name "MappingProfile" this name can anything unique and good to understand.

In this class, we are going to Maintain all Mappings.

Step 4. Initializing Mapper in Startup "ConfigureServices"

In Startup Class, we Need to Initialize Profile which we have created and also Register AutoMapper Service.

  Mapper.Initialize(cfg => cfg.AddProfile<MappingProfile>());



  services.AddAutoMapper();

Code Snippet to show ConfigureServices Method where we need to Initialize and Register AutoMapper.

public class Startup

{

    public Startup(IConfiguration configuration)

    {

        Configuration = configuration;

    }



    public IConfiguration Configuration { get; }





    public void ConfigureServices(IServiceCollection services)

    {

        services.Configure<CookiePolicyOptions>(options =>

        {

            // This lambda determines whether user consent for non-essential cookies is needed for a given request.

            options.CheckConsentNeeded = context => true;

            options.MinimumSameSitePolicy = SameSiteMode.None;

        });





        // Start Registering and Initializing AutoMapper



        Mapper.Initialize(cfg => cfg.AddProfile<MappingProfile>());

        services.AddAutoMapper();



        // End Registering and Initializing AutoMapper



        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);



    }}

Step 5. Get Output.

To Get Mapped result we need to call AutoMapper.Mapper.Map and pass Proper Destination and Source.

AutoMapper.Mapper.Map<Destination>(source);

CodeSnippet

    [HttpPost]

    public void Post([FromBody] SchemeMasterViewModel schemeMaster)

    {

        if (ModelState.IsValid)

        {

            var mappedresult = AutoMapper.Mapper.Map<SchemeMaster>(schemeMaster);

        }

    }

I am using AutoMapper 6.1.1 and asp.net Core 1.1.2.

First of all, define Profile classes inherited by Profile Class of Automapper. I Created IProfile interface which is empty, the purpose is only to find the classes of this type.

 public class UserProfile : Profile, IProfile

    {

        public UserProfile()

        {

            CreateMap<User, UserModel>();

            CreateMap<UserModel, User>();

        }

    }

Now create a separate class e.g Mappings

 public class Mappings

    {

     public static void RegisterMappings()

     {            

       var all =

       Assembly

          .GetEntryAssembly()

          .GetReferencedAssemblies()

          .Select(Assembly.Load)

          .SelectMany(x => x.DefinedTypes)

          .Where(type => typeof(IProfile).GetTypeInfo().IsAssignableFrom(type.AsType()));



            foreach (var ti in all)

            {

                var t = ti.AsType();

                if (t.Equals(typeof(IProfile)))

                {

                    Mapper.Initialize(cfg =>

                    {

                        cfg.AddProfiles(t); // Initialise each Profile classe

                    });

                }

            }         

        }



    }

Now in MVC Core web Project in Startup.cs file, in the constructor, call Mapping class which will initialize all mappings at the time of application
loading.

Mappings.RegisterMappings();

services.AddAutoMapper(); didn't work for me. (I am using Asp.Net Core 2.0)

After configuring as below

   var config = new AutoMapper.MapperConfiguration(cfg =>

   {                 

       cfg.CreateMap<ClientCustomer, Models.Customer>();

   });

initialize the mapper
IMapper mapper = config.CreateMapper();

and add the mapper object to services as a singleton
services.AddSingleton(mapper);

this way I am able to add a DI to controller

  private IMapper autoMapper = null;



  public VerifyController(IMapper mapper)

  {              

   autoMapper = mapper;  

  }

and I have used as below in my action methods

  ClientCustomer customerObj = autoMapper.Map<ClientCustomer>(customer);

For ASP.NET Core, the following is direct from Automapper and is 1 line in your startup class:
https://github.com/AutoMapper/AutoMapper.Extensions.Microsoft.DependencyInjection/blob/master/README.md

Simply add some profile classes. Then add below to your startup.cs class.
services.AddAutoMapper(OneOfYourProfileClassNamesHereSoItCanFindYourProfileAssembly)

Then simply Inject IMapper in your controllers or wherever you need it:

public class EmployeesController {

    private readonly IMapper _mapper;



    public EmployeesController(IMapper mapper)

        => _mapper = mapper;



    // use _mapper.Map to map

}

And if you want to use ProjectTo its now simply:

var customers = await dbContext.Customers.ProjectTo<CustomerDto>(_mapper.ConfigurationProvider).ToListAsync()

about theutz answer ,
there is no need to specify the IMapper mapper parrameter at the controllers constructor.

you can use the Mapper as it is a static member at any place of the code.

public class UserController : Controller {

   public someMethod()

   {

      Mapper.Map<User, UserDto>(user);

   }

}

To add onto what Arve Systad mentioned for testing. If for whatever reason you're like me and want to maintain the inheritance structure provided in theutz solution, you can set up the MapperConfiguration like so:

var mappingProfile = new MappingProfile();

var config = new MapperConfiguration(cfg =>

{

    cfg.AddProfile(mappingProfile);

});

var mapper = new Mapper(config);

I did this in NUnit.