将DTO映射到实体

Question

这些是我的Entities：在这种情况下，每个用户都可以创建一个Post。每个帖子可以有一个Items列表，每个项目都可以有一个带有标签的用户列表。

public class Post
{
    public int Id { get; set; }
    public int UserId { get; set; }
    public string Body { get; set; }
    public int LikeCount { get; set; }
    public PostStatuses Status { get; set; }

    [ForeignKey("UserId")]
    public User User { get; set; }

    public List<PostItem> PostItems { get; set; }

    public Post()
    {
        PostItems = new List<PostItem>();
    }
}

public class PostItem
{
    public int Id { get; set; }
    public int PostId { get; set; }
    public long AttachmentId { get; set; }  // Refer to CDN file Id

    [ForeignKey("PostId")]
    public Post Post { get; set; }

    public List<PostItemTag> TaggedUsers { get; set; }
}

public class PostItemTag
{
    public int PostItemId { get; set; }
    public int TaggedUserId { get; set; }
    public int X { get; set; }
    public int Y { get; set; }

    [ForeignKey("PostItemId")]
    public PostItem PostItem { get; set; }

    [ForeignKey("UserId")]
    public User User { get; set; }
}

这些是我的DTO：

public class CreatePostRequestDTO
{
    public int UserId { get; set; }
    public string Body { get; set; }
    public List<PostItemDTO> PostItems { get; set; }
}

public class PostItemDTO
{
    public long AttachmentId { get; set; }
    public List<PostItemTagDTO> TaggedUsers { get; set; }
}

public class PostItemTagDTO
{
    public int UserId { get; set; }
    public int X { get; set; }
    public int Y { get; set; }
}

这是我的API：

    public async Task<BaseResponseDTO<bool>> CreatePost(CreatePostRequestDTO createPostRequestDTO)
    {
        Post post = new Post()
        {
            Body = createPostRequestDTO.Body,
            Status = PostStatuses.Posted,
            UserId = createPostRequestDTO.UserId,
        };
        post.Mentions = createPostRequestDTO.Mentions.Select(x => new PostMention()
        {
            Post = post,
            UserId = x,
        }).ToList();

        post.PostItems = createPostRequestDTO.PostItems.Select(x => new PostItem()
        {
            AttachmentId = x.AttachmentId,
            Post = post,
            PostAttachmentType = x.PostAttachmentType,
            TaggedUseres = x.TaggedUseres.Select(c => new PostItemTag()
            {
                UserId = c.UserId,
                X = c.X,
                Y = c.Y,
                PostItemId = ? // My problem is here.
            }).ToList(),
        }).ToList();

        ...
    }

我该如何解决？

编辑： 一些多余的代码已被删除。

Edit2： 并且还删除了一些额外的说明。

Answer 1

对于与Stores : { Name: Countries : { Name: States : { Name: } } 的模型绑定，请执行以下步骤：

1. 安装软件包Automapper和AutoMapper
2. 将AutoMapper.Extensions.Microsoft.DependencyInjection添加到services.AddAutoMapper(typeof(Startup));

3. 像

   一样添加Startup.cs

   ModelProfile.cs

4. UseCase

   public class ModelProfile: Profile
   {
       public ModelProfile()
       {
           CreateMap<CreatePostRequestDTO, Post>();
           CreateMap<PostItemDTO, PostItem>();
           CreateMap<PostItemTagDTO, PostItemTag>();
       }
   }