EF Core - 当我指定自己的外键时，会自动添加不需要的外键

Question

我的 GroceryItemGroceryStores 多对多连接 table 中似乎有重复的外键：VeganItemId、VeganItemsId、EstablishmentId、EstablishmentsId.

我实际上只是在使用 VeganItemId 和 EstablishmentId，它们是唯一被添加到的。它会自动向我的 table 添加 VeganItemsId 和 EstablishmentsId 列。我怎么告诉它不要这样做？:

我的数据库的这张图片显示了有效的外键：

我的数据库上下文：

modelBuilder.Entity<GroceryItem>(gi =>
{
    gi.HasIndex(e => new { e.Brand, e.Name }).IsUnique();
    gi.HasKey(e => e.Id);
    gi.Property(e => e.Tags)
    .HasConversion(
        v => JsonSerializer.Serialize(v, null),
        v => JsonSerializer.Deserialize<List<GroceryItemTag>>(v, null),
        new ValueComparer<IList<GroceryItemTag>>(
            (c1, c2) => c1.SequenceEqual(c2),
            c => c.Aggregate(0, (a, v) => HashCode.Combine(a, v.GetHashCode())),
            c => (IList<GroceryItemTag>)c.ToList()));

});

modelBuilder.Entity<GroceryStore>(gs =>
{
    gs.HasIndex(gs => gs.PlaceId).IsUnique();

    gs.HasMany(gs => gs.VeganItems)
    .WithMany(vi => vi.Establishments)
    .UsingEntity<GroceryItemGroceryStore>
        (gigs => gigs.HasOne<GroceryItem>().WithMany(),
        gigs => gigs.HasOne<GroceryStore>().WithMany());
});

modelBuilder.Entity<GroceryItemGroceryStore>(gigs =>
{
    gigs.HasIndex(e => new { e.VeganItemId, e.EstablishmentId }).IsUnique();
    gigs.HasKey(e => new { e.VeganItemId, e.EstablishmentId });
});

public DbSet<GroceryItem> GroceryItems { get; set; }
public DbSet<GroceryItemGroceryStore> GroceryItemGroceryStores { get; set; }
public DbSet<GroceryStore> GroceryStores { get; set; }

我的tables:

public class GroceryStore
{   
    [Key]
    public Int64 Id { get; set; }
    [Required]
    public string Name { get; set; }
    [Required]
    public string PlaceId { get; set; }
    [Required]
    public string Street { get; set; }
    public string Suburb { get; set; }
    public string City { get; set; }
    public string StreetNumber { get; set; }

    public virtual ICollection<GroceryItem> VeganItems { get; set; }

}

public class GroceryItem
{
    [Key]
    public Int64 Id { get; set; }
    [Required]
    public string Name { get; set; }
    [Required]
    public string Description { get; set; }
    public string Image { get; set; }
    [Required]
    public int IsNotVeganCount { get; set; }
    [Required]
    public int IsVeganCount { get; set; }
    [Required]
    public int RatingsCount { get; set; }
    [Required]
    public int Rating { get; set; }
    [Required]
    public List<GroceryItemTag> Tags { get; set; }
    [Required]
    public int CurrentRevisionId { get; set; }
    public virtual ICollection<GroceryStore> Establishments { get; set; }
}

public class GroceryItemGroceryStore
{
    [Key]
     public Int64 Id { get; set; }
    [Key, Column(Order = 0), Required]
    public int VeganItemId { get; set; }
    [Key, Column(Order = 1), Required]
    public int EstablishmentId { get; set; }

    public virtual GroceryItem VeganItem { get; set; }
    public virtual GroceryStore Establishment { get; set; }

    [Required]
    public int NotInEstablishmentCount { get; set; }
    [Required]
    public int InEstablishmentCount { get; set; }
    [Required]
    public double Price { get; set; }

}

甚至像这样添加 .HasForeignKey(o => o.VeganItemId):

modelBuilder.Entity<GroceryStore>(gs =>
{
    gs.HasIndex(gs => gs.PlaceId).IsUnique();

    gs.HasMany(gs => gs.VeganItems)
    .WithMany(vi => vi.Establishments)
    .UsingEntity<GroceryItemGroceryStore>
        (gigs => gigs.HasOne<GroceryItem>().WithMany().HasForeignKey(o => o.EstablishmentId),
        gigs => gigs.HasOne<GroceryStore>().WithMany().HasForeignKey(o => o.VeganItemId));
});

使 table 有 VeganItemId1 和 EstablishmentId1:

编辑：我已经尝试从所有迁移文件中删除所有出现的 VeganItemsId 和 EstablishmentsId，但是当插入到数据库时它仍然认为它需要插入 EstablishmentsId。

Answer 1

此类 FK 的存在清楚地表明关系配置错误，通常发生在您从流畅配置中遗漏一些关系导航属性时，在这种情况下，EF 将它们映射到具有传统 FK 的单独 FK 关系 property/column 名字。

在这种特殊情况下，错误配置就在这里

gigs => gigs.HasOne<GroceryItem>().WithMany() // (1)

和

gigs.HasOne<GroceryStore>().WithMany() // (2)

因为您遗漏了 GroceryItemGroceryStore

的导航属性

public virtual GroceryItem VeganItem { get; set; } // (1)
public virtual GroceryStore Establishment { get; set; } // (2)

可能它们最初不存在，您后来添加了它们。但是你应该始终保持流畅的配置与模型同步，在这种情况下当然应该像

gigs => gigs.HasOne(e => e.VeganItem).WithMany()

和

gigs.HasOne(e => e.Establishment).WithMany()

Answer 2

您的问题是您已将 VeganItemId 和 EstablishmentId 定义为 复合主键 的一部分GroceryItemGroceryStore 的，与 Id

的 Artificitial 键结合使用

It is not necessary and even counter productive to define a composite key that includes a column that is already unique for all rows in the table, if there is a single column that is unique for all records, and you were going to include it in the primary key, then you should just use that column as the PK.

您的流畅配置与您的属性配置冲突，我建议至少部分解决方案如下：

public class GroceryItemGroceryStore
{
    [Key]
    public Int64 Id { get; set; }
    [ForeignKey(nameof(VeganItem)), Column(Order = 0), Required]
    public int VeganItemId { get; set; }
    [ForeignKey(nameof(Establishment)), Column(Order = 1), Required]
    public int EstablishmentId { get; set; }

    public virtual GroceryItem VeganItem { get; set; }
    public virtual GroceryStore Establishment { get; set; }

    [Required]
    public int NotInEstablishmentCount { get; set; }
    [Required]
    public int InEstablishmentCount { get; set; }
    [Required]
    public double Price { get; set; }

}

Answer 3

在GroceryItemGroceryStore中将VeganItemId和EstablishmentId的类型改为Int64，使它们与GroceryItem和GroceryItem中对应主键的类型匹配GroceryStore -

[Column(Order = 0), Required]
public Int64 VeganItemId { get; set; }       // Key attribute is not needed here
[Column(Order = 1), Required]
public Int64 EstablishmentId { get; set; }   // Key attribute is not needed here

修改 GroceryStore 的配置以包含导航属性并显式配置外键 -

builder.Entity<GroceryStore>(gs =>
{
    gs.HasIndex(gs => gs.PlaceId).IsUnique();

    gs.HasMany(gs => gs.VeganItems)
    .WithMany(vi => vi.Establishments)
    .UsingEntity<GroceryItemGroceryStore>
        (gigs => gigs.HasOne(p => p.VeganItem)
                    .WithMany().HasForeignKey(p => p.VeganItemId),
        gigs => gigs.HasOne(p => p.Establishment)
                    .WithMany().HasForeignKey(p => p.EstablishmentId));
});

这应该可以解决重复键问题。

此外，您应该从 GroceryItemGroceryStore -

中删除以下属性

[Key]
public Int64 Id { get; set; }

因为您正在通过 fluent 配置复合主键 API。

EF Core - 当我指定自己的外键时，会自动添加不需要的外键

EF Core - Unwanted foreign keys being added automatically when I specify my own ones

c#

entity-framework-core

.net-5