AutoMapper.AutoMapperMappingException：.NET CORE 中缺少类型映射配置或不支持的映射

Question

我在 .NET CORE 应用程序中使用 AutoMapper。我在 ConfigureServices.cs 方法文件中的 Startup.cs 中配置了 AutoMapper，如下所示：

public void ConfigureServices(IServiceCollection services)
        {

             /* Some Code */
            
            /* AutoMapper Configuration */
            services.AddAutoMapper(typeof(AutoMapperProfileConfiguration).GetType().Assembly);

            services.AddMvcCore();

             /* Some Code */
        }

AutoMapperProfileConfiguration 如下：

public class AutoMapperProfileConfiguration : Profile
    {
        public AutoMapperProfileConfiguration()
        {
            CreateMap<LoginRequestDto, Users>();
        }
    }

然后我在下面的课程中使用了这个映射器：

public LoginResponseDto CreateAnAccount(LoginRequestDto loginRequestDto)
        {
            var userInfo = _mapper.Map<Users>(loginRequestDto);
            userInfo.Id = Guid.NewGuid();
            _context.InsertItem<Users>(userInfo);
            var insertedUserDetails = _context.GetItemById<Users>(userInfo.Id);
            insertedUserDetails.Wait();
            return _mapper.Map<LoginResponseDto>(insertedUserDetails.Result);
        }

但是当我尝试将loginRequestDto 中存在的数据映射到Users 类时，它给了我以下异常：

AutoMapper.AutoMapperMappingException: Missing type map configuration or unsupported mapping.

Mapping types:
Object -> Users
System.Object -> NeighborhoodHelpers.UserMicroservice.Entities.Models.Users
   at lambda_method(Closure , Object , Users , ResolutionContext )
   at NeighborhoodHelpers.UserMicroservice.DataAccessProvider.UserDataAccess.UserDataAccess.CreateAnAccount(LoginRequestDto loginRequestDto) in D:\Gursimran\Hackathon2\NeighborhoodHelpers.UserMicroservice.API\NeighborhoodHelpers.UserMicroservice.DataAccessProvider\UserDataAccess\UserDataAccess.cs:line 29
   at NeighborhoodHelpers.UserMicroservice.Services.UserServices.UserService.CreateAnAccount(LoginRequestDto loginRequestDto) in D:\Gursimran\Hackathon2\NeighborhoodHelpers.UserMicroservice.API\NeighborhoodHelpers.UserMicroservice.Services\UserServices\UserService.cs:line 22
   at NeighborhoodHelpers.UserMicroservice.API.Controllers.LoginController.CreateAnAccount(LoginRequestDto loginRequestDto) in D:\Gursimran\Hackathon2\NeighborhoodHelpers.UserMicroservice.API\NeighborhoodHelpers.UserMicroservice.API\Controllers\LoginController.cs:line 34
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

我正在使用 .NET Core 3.1。请帮我解决一下这个。我无法使用 AutoMapper 功能。

Answer 1

如下更改您的 Startup.cs：

services.AddAutoMapper(typeof(AutoMapperProfileConfiguration));

Answer 2

在您的代码中，AutoMapper 的配置看起来没有看到定义的配置文件，为了更正它，我建议使用 以下两个选项之一。

选项 1： NuGet 包 AutoMapper

1. 对于 Flexibility 和 Cleaner Code，定义一个扩展方法以添加当前的 AutoMapperProfileConfiguration 以及未来需要的许多其他方法。李>
2. 打电话给Startup.cs

CustomAutoMapper.cs：

using AutoMapper;
using Microsoft.Extensions.DependencyInjection;

namespace MyApp.CustomConfiguration
{
    public static class CustomAutoMapper
    {
        public static void AddCustomConfiguredAutoMapper(this IServiceCollection services)
        {
            var config = new MapperConfiguration(cfg =>
            {
                cfg.AddProfile(new AutoMapperProfileConfiguration());
            });

            var mapper = config.CreateMapper();

            services.AddSingleton(mapper);
        }
    }
}

在 Startup.cs 中：

services.AddCustomConfiguredAutoMapper();

选项 2： 使用 AutoMapper.Extensions.Microsoft.DependencyInjection Nuget 包（我个人更喜欢使用两年以上，因为我在解决方案中使用了多个程序集并且这个包为 Profiles 提供了自动发现，因为它自动扫描任何继承自 AutoMapper 的 Profile 类的类的解决方案。

只需在您的 Startup.cs 中：

services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());

Answer 3

查看 Users 和 LoginRequestDto 的属性可以更轻松地回答您的问题。因为从错误消息中可以理解，有些属性需要“忽略”，或者您正在做诸如将字典转换为列表之类的事情。

如果你能展示你的课程，也许我们可以相应地安排以下行并解决问题。

CreateMap<LoginRequestDto, Users>();