AutoMapper 實體到 Dto 轉換：映射類型錯誤

Question

我的實體中有不應該暴露給外部的數據。 所以我想通過將實體映射到 dto 來導出實體。 我收到的數據類型為IList<Article> 。 我需要將其轉換為IList<ArticleBasicDto>但是當我嘗試這樣做時出現錯誤。

我嘗試以這種方式將IList<ArticleBasicDto>導出為目標，但失敗了。 由於我剛剛學習，我無法達到結果，我該怎么辦？

我這樣做的原因是因為文章中有關用戶實體的信息太多。 另外在JSON output中的文章Object中有一個Category字段，屬於該Category的文章在該字段中重新列出。 我正在嘗試使用 Dto 來擺脫這些不必要的字段。

錯誤信息

處理請求時發生未處理的異常。 AutoMapperMappingException：缺少類型 map 配置或不支持的映射。

映射類型：文章 -> ArticleBasicDto Blog.Entities.Concrete.Article -> Blog.Entities.Dtos.ArticleBasicDto lambda_method178(Closure, Article, ArticleBasicDto, ResolutionContext )

AutoMapperMappingException：錯誤映射類型。

映射類型：IList 1 -> IList 1 System.Collections.Generic.IList 1[[Blog.Entities.Concrete.Article, Blog.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]] -> System.Collections.Generic.IList 1[[Blog.Entities.Dtos.ArticleBasicDto, Blog.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]] lambda_method177(Closure, IList, IList, ResolutionContext )

映射器配置文件

namespace Blog.Business.AutoMapper.Profiles
{
    public class ArticleProfile : Profile
    {
        public ArticleProfile()
        {
           CreateMap<Article, ArticleBasicDto>().ForMember(dest => dest.Category, opt => opt.MapFrom(x => x.Category)).ForMember(dest => dest.User,
                opt => opt.MapFrom(x => x.User));
        }
    }
}

Dtos

namespace Blog.Entities.Dtos
{
    public class ArticleBasicDto
    {
        public string Title { get; set; }
        public string Content { get; set; }
        public string Thumbnail { get; set; }
        public DateTime Date { get; set; }
        public int ViewsCount { get; set; } = 0;
        public int CommentCount { get; set; } = 0;
        public UserBasicDto User { get; set; }
        public CategoryBasicDto Category { get; set; }
    }
}

namespace Blog.Entities.Dtos
{
    public class CategoryBasicDto
    {
        public string Name { get; set; }
        public string Description { get; set; }
        public string Slug { get; set; }
    }
}

namespace Blog.Entities.Dtos
{
    public class UserBasicDto
    {
        public string Email { get; set; }
        public string Username { get; set; }
        public string Picture { get; set; }
    }
}

經理GetAllBasic方法

public async Task<IDataResult<ArticleBasicListDto>> GetAllBasic()
        {
            var results = await _unitOfWork.Articles.GetAllAsync();
            var mapping = _mapper.Map<IList<ArticleBasicDto>>(results);
            return new DataResult<ArticleBasicListDto>(ResultStatus.Success, new ArticleBasicListDto()
            {
                Articles = mapping,
            });
        }

MVC 層 - Startup.cs

namespace Blog.MVC
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews().AddRazorRuntimeCompilation().AddNewtonsoftJson(opt => opt.SerializerSettings.ReferenceLoopHandling
                = Newtonsoft.Json.ReferenceLoopHandling.Ignore);
            services.AddAutoMapper(typeof(Startup));
            services.LoadMyServices();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseStatusCodePages();
            }

            app.UseStaticFiles();

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapAreaControllerRoute(
                    name: "Admin",
                    areaName: "Admin",
                    pattern: "Admin/{controller=Home}/{action=Index}/{id?}"
                );
                endpoints.MapDefaultControllerRoute();
                endpoints.MapControllers();
            });
        }
    }
}

Answer 1

要解決此問題，您必須將startup class 替換為如下所示的ArticleProfile services.AddAutoMapper(typeof(ArticleProfile ));

它將解決您的問題。

Answer 2

您需要為用戶和類別定義映射

CreateMap<User,CategoryBasicDto>();
CreateMap<Category,CategoryBasicDto>();