Unable to resolve service for type ‘automapper.imapper’ while attempting to activate

Explanation:

The error message “unable to resolve service for type ‘automapper.imapper’ while attempting to activate” indicates that the dependency injection container is unable to find a suitable implementation for the ‘automapper.imapper’ interface.

To resolve this issue, you need to register the AutoMapper package and configure it properly in your application startup file.

Example:

Let’s assume you have a .NET Core web application, and you want to use AutoMapper to map objects.

1. Add the AutoMapper NuGet package to your project:

dotnet add package AutoMapper

2. In your startup file (e.g., Startup.cs), configure AutoMapper in the ‘ConfigureServices’ method:

using AutoMapper;
        
        public void ConfigureServices(IServiceCollection services)
        {
            // Other service configurations...
        
            // Add AutoMapper
            services.AddAutoMapper(typeof(Startup));
        
            // Other configurations...
        }

3. Create a mapping profile that inherits from ‘Profile’ and add your mappings:

using AutoMapper;

        public class MappingProfile : Profile
        {
            public MappingProfile()
            {
                CreateMap<SourceObject, DestinationObject>();
            }
        }

4. Use AutoMapper in your code by injecting the ‘IMapper’ interface:

using AutoMapper;
        using Microsoft.AspNetCore.Mvc;

        public class MyController : Controller
        {
            private readonly IMapper _mapper;

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

            public IActionResult Index()
            {
                var sourceObject = new SourceObject();
                var destinationObject = _mapper.Map<DestinationObject>(sourceObject);
        
                // Other code...
        
                return View(destinationObject);
            }
        }