EF Core 创建多个外键列 [英] EF Core creates multiple foreign key columns
问题描述
我将 EF Core 与 .NET Core 3.1 一起使用
I'm using EF Core with .NET Core 3.1
我有一个简单的客户端-事件关系示例:
I have simple example of Client-Event relationship:
public class BaseEntity
{
[Key]
[Required]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public DateTime CreatedOn { get; set; }
public DateTime? ModifiedOn { get; set; }
}
public class Client : BaseEntity
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public string Phone { get; set; }
}
public class Event : BaseEntity
{
public DateTime Start { get; set; }
public DateTime End { get; set; }
public Client Client { get; set; }
}
在我的上下文中，我使用 Fluent API 来指定关系:
In my context, I'm using Fluent API to specify relationships:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Event>()
.HasOne<Client>()
.WithMany()
.IsRequired()
.OnDelete(DeleteBehavior.Cascade);
}
当我创建迁移时，客户端表看起来不错，但事件表看起来像这样:
When I create migration, the client table looks fine, but the event table looks like this:
migrationBuilder.CreateTable(
name: "Events",
columns: table => new
{
Id = table.Column<int>(nullable: false)
.Annotation("SqlServer:Identity", "1, 1"),
CreatedOn = table.Column<DateTime>(nullable: false),
ModifiedOn = table.Column<DateTime>(nullable: true),
Start = table.Column<DateTime>(nullable: false),
End = table.Column<DateTime>(nullable: false),
ClientId = table.Column<int>(nullable: false),
ClientId1 = table.Column<int>(nullable: false)
},
constraints: table =>
{
table.PrimaryKey("PK_Events", x => x.Id);
table.ForeignKey(
name: "FK_Events_Clients_ClientId",
column: x => x.ClientId,
principalTable: "Clients",
principalColumn: "Id",
onDelete: ReferentialAction.Cascade);
table.ForeignKey(
name: "FK_Events_Clients_ClientId1",
column: x => x.ClientId1,
principalTable: "Clients",
principalColumn: "Id",
onDelete: ReferentialAction.Cascade);
});
最后我得到了两列:ClientId 和 ClientId1.为什么实体框架会为我的关系创建两列?
Finally I end up having two columns: ClientId and ClientId1. Why is Entity Framework creating two columns for my relationship?
到目前为止，我没有使用 Fluent API，它仅与自动生成的影子属性 ClientId 完美配合，但我需要从该实体配置级联删除，并且由于没有其他方法可以做到这一点，我指定了关系如上图.从那时起，它就有了额外的外键列.
I wasn't using Fluent API so far and it worked perfectly with just shadow property ClientId auto-generated, but I needed to configure cascade delete form this entities, and since there is no other way to do it, I specified the relationship as pictured above. Since then, there is additional foreign key column for it.
我尝试指定一个外键列:
I tried specifying a foreign key column:
modelBuilder.Entity<Event>()
.HasOne<Client>()
.WithMany()
.IsRequired()
.HasForeignKey("ClientId")
.OnDelete(DeleteBehavior.Cascade);
目前没有效果.有没有办法告诉 EF im 使用自动生成的阴影属性?
No effect so far. Is there any way to tell EF im using auto generated shadow properties?
编辑 #1:
我也尝试过像这样自己指定外键属性:
I also tried specyfing Foreign keys properties on my own like this:
public class Event : BaseEntity
{
public DateTime Start { get; set; }
public DateTime End { get; set; }
public int ClientId { get; set; }
public Client Client { get; set; }
}
然后
modelBuilder.Entity<Event>()
.HasOne<Client>()
.WithMany()
.IsRequired()
.HasForeignKey(e => e.ClientId)
.OnDelete(DeleteBehavior.Cascade);
但是还是没有效果.
推荐答案
事实证明，关系可以是空的 - 将决定留给框架，但这并不能真正满足您的兴趣.我修改了我的代码，所以有明确的指向导航属性，EF 识别出这种关系并停止为列创建阴影属性:
It turns out, relationships can be empty - leaving decision to the framework, but it doesn't really serve Your interest. I modified my code, so there is explicit pointing at the navigation property, and EF recognized the relationship and stopped creating shadow properties for the columns:
modelBuilder.Entity<Event>()
.HasOne<Client>(e => e.Client)
.WithMany()
.IsRequired()
.OnDelete(DeleteBehavior.Cascade);
这篇关于EF Core 创建多个外键列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
