使用 swagger 在 Web Api 中实现 EF 多对多关系

Question

当我尝试在 EF Core 中设置多对多关系并在 Swagger 中捕获结果时遇到问题。

public class  Book
{
    [Key]
    public int BookId { get; set; }
    public string? BookName { get; set; }
}

public class  Publisher
{
    [Key]
    public int PublisherId { get; set; }
    public string? PublisherName { get; set; }
    public ICollection<BookPublisher? BookPublishers { get; set; }
}

public class BookPublisher
{
    [Key]
    public int BookPublisherId { get; set; }
    public int BookId { get; set; }
    public int PublisherId { get; set; }

    public Book? Book { get; set; }
}

在

DbContext

中，我有：

DbSet<Publisher>? Publishers { get; set; }
DbSet<BookPublisher>? BookPublishers { get; set; }
DbSet<Book>? Books { get; set; }

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.Entity<Publisher>().ToTable("TAB_Publisher", "dbo");
    builder.Entity<BookPublisher>().ToTable("TAB_BookPublisher", "dbo");
    builder.Entity<Book>().ToTable("TAB_Book", "dbo");
}

public List<Publisher>? GetPublishers()
{
    if (Publishers != null)
        return Publishers
               .Include(s => s.BookPublishers).ThenInclude(s => s.Book)
               .ToList<Publisher>();
    else
        return null;
}

当我在 Swagger 中调用我的方法

GetPublishers

时，我得到了我想要的：

[
  {
    "PublisherId": 1,
    "PublisherName": "GrpPdcTestTGO",
    "BookPublisher": [
      {
        "BookPublisherId": 1,
        "BookId": 1,
        "PublisherId": 1,
        "Book": {
          "BookId": 1,
          "BookName": "TEST1",
        }
      },
      {
        "BookPublisherId": 2,
        "BookId": 2,
        "PublisherId": 1,
        "Book": {
          "BookId": 2,
          "BookName": "TEST2",
        }
      },
    ]
  }
]

怎样才能得到与书本相同的结果？一本书可以有多个出版商。我必须建立什么样的关系？

Answer 1

你是对的，我有一个循环引用，但这很正常，因为我的 CDM 是这样的： 在此输入图片描述

我将有 2 个方法 GetPublishers 和 GetBooks。 当我得到 GetPublishers 的结果时，我想要这个

    [
  {
    "PublisherId": 1,
    "PublisherName": "NamePublisher1",
    "BookPublisher": [
      {
        "BookPublisherId": 1,
        "BookId": 1,
        "PublisherId": 1,
        "Book": {
          "BookId": 1,
          "BookName": "TEST1",
        }
      },
      {
        "BookPublisherId": 2,
        "BookId": 2,
        "PublisherId": 1,
        "Book": {
          "BookId": 2,
          "BookName": "TEST2",
        }
      },
    ]
  }
]

当我想要 GetBooks 的结果时，结果必须是这样的

[
  {
    "BookId": 1,
    "BookName": "TEST1",
    "BookPublisher": [
      {
        "BookPublisherId": 1,
        "BookId": 1,
        "PublisherId": 1,
        "Publisher": {
          "PublisherId": 1,
          "PublisherName": "NamePublisher1",
        }
      }
    ]
  },
  {
    "BookId": 2,
    "BookName": "TEST2",
    "BookPublisher": [
      {
        "BookPublisherId": 2,
        "BookId": 2,
        "PublisherId": 1,
        "Publisher": {
          "PublisherId": 1,
          "PublisherName": "NamePublisher1",
        }
      }
    ]
  }
]

所以我之前的类定义都可以，并且在方法“OnModelCreating”上我没有放置关系。