多次使用导航属性 C# EF Core

Question

我有这个数据库结构

public class Gameboard
{
    public string Id { get; set; }
    public int Round { get; set; }
    public int MaxTries { get; set; }
    public ICollection<ColorGameBoard> Colors { get; set; }
    public ICollection<ColorGameBoard> CorrectColors { get; set; }

}
public class Color
{
    public int Id { get; set; }
    public string Name { get; set; }

    public ICollection<ColorGameBoard> ColorGameBoards { get; set; }

}
public class ColorGameBoard
{
    public int Id { get; set; }
    public int GameBoardId { get; set;}
    public Gameboard Gameboard { get; set; }
    public int CorrectColorId { get; set; }
    public Color CorrectColors { get; set; }
    public int ColorId { get; set; }
    public Color Color { get; set; }

}

这就是我创建关系的方式：

  modelBuilder.Entity<ColorGameBoard>()
            .HasOne(x => x.Gameboard)
            .WithMany(x => x.CorrectColors)
            .HasForeignKey(x => x.CorrectColorId);

        modelBuilder.Entity<ColorGameBoard>()
          .HasOne(x => x.Gameboard)
          .WithMany(x => x.Colors)
          .HasForeignKey(x => x.ColorId);

        modelBuilder.Entity<ColorGameBoard>()
           .HasOne(x => x.Color)
           .WithMany(x => x.ColorGameBoards)
           .HasForeignKey(x => x.GameBoardId);

我收到此错误：

无法在“Gameboard.Colors”和“ColorGameBoard.Gameboard”之间创建关系，因为“Gameboard.CorrectColors”和“ColorGameBoard.Gameboard”之间已经存在关系。导航属性只能参与单个关系。如果您想在“OnModelCreating”中首先在导航“ColorGameBoard.Gameboard”上覆盖现有关系调用“Ignore”。

数据库结构：在 Gameboard 上有两个带颜色的列表。每个列表应包含至少 5 种颜色。并且数据库中的每种颜色都可以在多个游戏板上使用。此外，一种颜色可以在游戏板上多次使用。

有人知道如何解决这个错误吗？

Answer 1

您的代码中存在一些对比关系问题。 Gameboard 类中有两个ICollection<ColorGameBoard>，但ColorGameBoard 类中只有一个 Gameboard。这样，在构建数据库的时候就会出错。比较关系的数量应该是一致的。在 EF Core 中构建 InverseProperty 属性时，可以使用一些属性，例如：virtual,ForeignKey,InverseProperty。

不知道你对数据库的需求是什么，所以我写了两个demo，下面是我的代码：

第一个demo，两个class Gameboard对应一个class Color。

Gameboard.class

public class Gameboard
    {
        public int Id { get; set; }
        public int Round { get; set; }
        public int MaxTries { get; set; }

        [InverseProperty("GameboardOne")]
        public ICollection<ColorGameBoard> OneBorad { get; set; }

        [InverseProperty("GameboardTwo")]
        public ICollection<ColorGameBoard> TwoBoard { get; set; }

    }

颜色类

public class Color
    {
        public int Id { get; set; }
        public string Name { get; set; }
        [InverseProperty("Color")]
        public ICollection<ColorGameBoard> ColorGameBoards { get; set; }
    }

ColorGameBoard.class

public class ColorGameBoard
    {
        public int Id { get; set; }

        [ForeignKey("GameboardOne")]
        public int OneId { get; set; }
        public virtual Gameboard GameboardOne { get; set; }

        [ForeignKey("GameboardTwo")]
        public int TwoId { get; set; }
        public virtual Gameboard GameboardTwo { get; set; }

        [ForeignKey("Color")]
        public int ColorId { get; set; }
        public virtual Color Color { get; set; }
    }

模型构建器

            modelBuilder.Entity<ColorGameBoard>()
                .HasOne(c => c.Color)
                .WithMany(a =>a.ColorGameBoards)
                .HasForeignKey(b => b.ColorId)
                .OnDelete(DeleteBehavior.NoAction);

            modelBuilder.Entity<ColorGameBoard>()
                .HasOne(d => d.GameboardOne)
                .WithMany(e => e.OneBorad)
                .HasForeignKey(b => b.OneId)
                .OnDelete(DeleteBehavior.NoAction); 

            modelBuilder.Entity<ColorGameBoard>()
                .HasOne(d => d.GameboardTwo)
                .WithMany(e => e.TwoBoard)
                .HasForeignKey(b => b.TwoId)
                .OnDelete(DeleteBehavior.NoAction); 

然后，就可以创建数据库了

第二个demo，一个class Gameboard对应两个class Color。

Gameboard.class

public class Gameboard
    {
        public int Id { get; set; }
        public int Round { get; set; }
        public int MaxTries { get; set; }
        [InverseProperty("Gameboard")]
        public ICollection<ColorGameBoard> Colors { get; set; }
        
    }

颜色类

public class Color
    {
        public int Id { get; set; }
        public string Name { get; set; }
        [InverseProperty("Color")]
        public ICollection<ColorGameBoard> ColorGameBoards { get; set; }
        [InverseProperty("CorrectColors")]
        public ICollection<ColorGameBoard> CorrectColors { get; set; }
    }

ColorGameBoard.class

public class ColorGameBoard
    {
        public int Id { get; set; }

        [ForeignKey("Gameboard")]
        public int GameBoardId { get; set; }
        public virtual Gameboard Gameboard { get; set; }

        [ForeignKey("CorrectColors")]
        public int CorrectColorId { get; set; }
        public virtual Color CorrectColors { get; set; }

        [ForeignKey("Color")]
        public int ColorId { get; set; }
        public virtual Color Color { get; set; }
    }

模型构建器

            modelBuilder.Entity<ColorGameBoard>()
                .HasOne(x => x.Gameboard)
                .WithMany(x => x.Colors)
                .HasForeignKey(x => x.GameBoardId)
                .OnDelete(DeleteBehavior.NoAction);

            modelBuilder.Entity<ColorGameBoard>()
              .HasOne(x => x.CorrectColors)
              .WithMany(x => x.CorrectColors)
              .HasForeignKey(x => x.CorrectColorId)
              .OnDelete(DeleteBehavior.NoAction);

            modelBuilder.Entity<ColorGameBoard>()
               .HasOne(x => x.Color)
               .WithMany(x => x.ColorGameBoards)
               .HasForeignKey(x => x.ColorId)
               .OnDelete(DeleteBehavior.NoAction);

然后，您可以创建数据库