Automapper: Missing type map configuration .NET Web API

Question

I am currently using a .NET Web API, to get a list of Counties based on Countries. While attempting to GET the Counties, I get the exception:

"Automapper: Missing type map configuration or unsupported mapping"

My Domain Class is :

 public class County
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string CountryId { get; set; }

        public virtual Country Country { get; set; }
        public virtual IList<City> City { get; set; }
    }

My DTO is

 public class CountyResponse
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string CountryId { get; set; }
    }

Mapping profile :

public class CountyProfile : Profile
    {
        public CountyProfile()
        {
            CreateMap<CountyResponse, County>().ReverseMap();
        }
    }

My Service Class GetAlLMethod:

 public async Task<Result<List<CountyResponse>>> GetAllAsync()
        {
            var counties = _context.Counties.ToListAsync();
            var mappedCounties = _mapper.Map<List<CountyResponse>>(counties);
            return await Result<List<CountyResponse>>.SuccessAsync(mappedCounties);
        }

Builds Ok, and I also have the Country domain mapped exactly the same (1:1). Yet, one works, while this one, when trying to access the Get Endpoint, i get this error. Any idea what is wrong here ? (the services are registered - I am using the following to inject them:

 public static void AddInfrastructureMappings(this IServiceCollection services)
        {
            services.AddAutoMapper(Assembly.GetExecutingAssembly());
        }

Answer 1

You are mapping a task (the result of your ToListAsync) to a list of your DTO which fails. You need to await your query so you get the result of the task, then the mapping will work properly

        var counties = await _context.Counties.ToListAsync();
        var mappedCounties = _mapper.Map<List<CountyResponse>>(counties);