AutoMapper in .NET

In .NET 6, you can use the built-in dependency injection (DI) container along with AutoMapper to set up mapping profiles. Here’s a step-by-step guide on how to configure dependency injection and AutoMapper in a .NET 6 program:

1. Create a new .NET 6 console application or web application (MVC, API, etc.) or use an existing one.

2. Install the required NuGet packages if you haven’t already:

dotnet add package AutoMapper.Extensions.Microsoft.DependencyInjection

3. Define your data models and DTOs. For example:

// Data model
public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

// Data Transfer Object (DTO)
public class ProductDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

4. Create AutoMapper profiles to define how your data models should be mapped to DTOs. Create a class that extends Profile and configure your mappings. For example:

public class MappingProfile : Profile
{
    public MappingProfile()
    {
        CreateMap<Product, ProductDto>();
    }
}

Alternatively your file might look like this

public class MappingProfile : Profile
{
    public MappingProfile()
    {
        CreateMap<ProductDocument, ProductDocument_DTO>();
        CreateMap<ProductModelDocument, ProductModelDocument_DTO>()
            .ForMember(dest => dest.Variants, opt => opt.Ignore());
   }
}

Or even simpler like that

public class MappingProfile : Profile
{
    public MappingProfile()
    {
        CreateMap<CollectionHeader_DTO,  CollectionHeader>().ReverseMap();
        CreateMap<ProductEntry_Header_DTO, ProductEntry_Header>().ReverseMap();
   }
}

5. Configure AutoMapper and Dependency Injection in your program’s Program.cs file. Here's a sample Program.cs: 

using AutoMapper;
using Microsoft.Extensions.DependencyInjection;

var builder = WebApplication.CreateBuilder(args);
var services = builder.Services;

// Add AutoMapper with a custom mapping profile
services.AddAutoMapper(typeof(MappingProfile));

// Configure other services
// ...

var app = builder.Build();

// Configure the app
// ...

app.Run();

6. With this setup, you can now use dependency injection to inject IMapper into your services or controllers:

public class ProductService
{
    private readonly IMapper _mapper;

    public ProductService(IMapper mapper)
    {
        _mapper = mapper;
    }

    public ProductDto MapProductToDto(Product product)
    {
        return _mapper.Map<ProductDto>(product);
    }
}

That’s it! You’ve set up AutoMapper and Dependency Injection in your .NET 6 program. You can now use ProductService (or any other service) to map your data models to DTOs.