How to create a reusable mapping profile with Mapster?

Updated: Couldn't find way to do what you are trying to do with Mapster, but here is an example of it working with Automapper.

using AutoMapper;
using System;

namespace ConsoleApp5
{
    class A { public string FirstName { get; set; } }

    public class B { public string Address1 { get; set; } }

    public class C
    {
        public string FirstName { get; set; }
        public string Address1 { get; set; }
    }

    public class DemoProfile : Profile
    {
        public DemoProfile()
        {
            CreateMap<(A, B), C>()
                .ForMember(dest=> dest.FirstName, opts => opts.MapFrom(src => src.Item1.FirstName))
                .ForMember(dest => dest.Address1, opts => opts.MapFrom(src => src.Item2.Address1));
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var config = new MapperConfiguration(cfg => {
                cfg.AddProfile<DemoProfile>();
            });

            var mapper = config.CreateMapper();
            var destination = mapper.Map<C>((new A {  FirstName = "Test" }, new B { Address1 = "Addr" }));

            Console.ReadKey();
        }
    }
}

Hey I haven't used Mapster before till now but here is what I gather. It is very specific about the type of tuple you use Tuple<T1,T2> over (T1,T2) but aside from that minor thing I was able to get it running and mapping without issues. Here is a small console example as example.

using Mapster;
using System;

namespace ConsoleApp5
{
    class A { public string FirstName { get; set; } }

    public class B { public string Address1 { get; set; } }

    public class C
    {
        public string FirstName { get; set; }
        public string Address1 { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            // Option 1
            TypeAdapterConfig<Tuple<A, B>, C>.NewConfig()
                .Map(dest => dest.FirstName, src => src.Item1.FirstName)
                .Map(dest => dest.Address1, src => src.Item2.Address1);

            var destObject = new Tuple<A, B>(new A { FirstName = "Test" }, new B { Address1 = "Address 1" })
                .Adapt<Tuple<A, B>, C>();

            // Option 2
            TypeAdapterConfig<(A, B), C>.NewConfig()
                .Map(dest => dest.FirstName, src => src.Item1.FirstName)
                .Map(dest => dest.Address1, src => src.Item2.Address1);

            var destObject2 = (new A { FirstName = "Test" }, new B { Address1 = "Address 1" })
                .Adapt<(A, B), C>();

            Console.ReadKey();
        }
    }
}

You can use next:

    var config = new TypeAdapterConfig()
    {
        RequireExplicitMapping = true,
        RequireDestinationMemberSource = true,
        Compiler = exp => exp.CompileFast()
    };

    config.Scan("Your assembly");

    services.AddSingleton(config);
    services.AddTransient<IMapper, ServiceMapper>();

    public class RegisterConfig : IRegister
    {
        public void Register(TypeAdapterConfig config)
        {
            config.NewConfig<TSource, TDestination>();
        }
    }

Where services is IServiceCollection

Based on @Felipe Ramos answer I wasn't able to solve it with Mapster but with Automapper. This is my solution just for the sake of completeness. Please let me know if there is a solution for Mapster!

I installed the packages

AutoMapper v10.1.1

AutoMapper.Extensions.Microsoft.DependencyInjection v8.1.1

Inside the method Startup.ConfigureServices I added the line services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());

The whole code then looks like

[ApiController]
[Route("[controller]")]
public class MyController : ControllerBase
{
    private readonly IMapper _mapper;
    
    public MyController(IMapper mapper)
    {
        _mapper = mapper;
    }
    
    [HttpGet]
    public ActionResult<UsernameWithTodoTitle> Get()
    {
        var user = new User { Username = "foo", FieldFromUser = "x" };
        var todo = new Todo { Title = "bar", FieldFromTodo = "y" };
        var usernameWithTodoTitle = _mapper.Map<UsernameWithTodoTitle>((user, todo));
    
        return Ok(usernameWithTodoTitle);
    }
}

public class User
{
    public string Username { get; set; }
    public string FieldFromUser { get; set; }
}

public class Todo
{
    public string Title { get; set; } // !! map this one to the TodoTitle field !!
    public string FieldFromTodo { get; set; }
}

public class UsernameWithTodoTitle
{
    public string Username { get; set; }
    public string TodoTitle { get; set; } // !! this one is special, is has a different name !!
    public string FieldFromUser { get; set; }
    public string FieldFromTodo { get; set; }
}

public class UsernameWithTodoTitleMappingProfile : Profile
{
    public UsernameWithTodoTitleMappingProfile()
    {
        CreateMap<(User, Todo), UsernameWithTodoTitle>()
            .ForMember(
                destination => destination.Username,
                memberOptions => memberOptions.MapFrom(source => source.Item1.Username))
            .ForMember(
                destination => destination.TodoTitle,
                memberOptions => memberOptions.MapFrom(source => source.Item2.Title))
            .ForMember(
                destination => destination.FieldFromUser,
                memberOptions => memberOptions.MapFrom(source => source.Item1.FieldFromUser))
            .ForMember(
                destination => destination.FieldFromTodo,
                memberOptions => memberOptions.MapFrom(source => source.Item2.FieldFromTodo));
    }
}