MVC5 EF6.1 代码第一个外键约束

Question

public class Names
{
    [Key]
    public int NameID { get; set; }
    [StringLength(100)]
    [Index(IsUnique = true)]
    [Required]
    public string Name { get; set; }
}
public class People
{
    [Key]
    public int PeopleID { get; set; }
    [Required]
    public int FirstNameID { get; set; }
    [ForeignKey("FirstNameID")]
    public Names FirstName { get; set; }
    public int MiddleNameID { get; set; }
    [ForeignKey("MiddleNameID")]
    public Names MiddleName { get; set; }
    public int LastNameID { get; set; }
    [ForeignKey("LastNameID")]
    public Names LastName { get; set; }
    public DateTime DateOfBirth { get; set; }
}

创建迁移并尝试更新数据库后，我收到以下错误：

Introducing FOREIGN KEY constraint 'FK_dbo.People_dbo.Names_LastNameID' on table 'People' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

无法创建约束或索引。请参阅以前的错误。

我

根据我在网上看到的其他文章将以下内容添加到上下文中，但它没有做我想要的。

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
    }

这是生成的迁移代码...

namespace MyDataSet.Migrations
{
    using System;
    using System.Data.Entity.Migrations;
    public partial class PeopleNameIDs : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "dbo.Names",
                c => new
                    {
                        NameID = c.Int(nullable: false, identity: true),
                        Name = c.String(nullable: false, maxLength: 100),
                    })
                .PrimaryKey(t => t.NameID)
                .Index(t => t.Name, unique: true);
            CreateTable(
                "dbo.People",
                c => new
                    {
                        PeopleID = c.Int(nullable: false, identity: true),
                        FirstNameID = c.Int(nullable: false),
                        MiddleNameID = c.Int(nullable: false),
                        LastNameID = c.Int(nullable: false),
                        DateOfBirth = c.DateTime(nullable: false),
                    })
                .PrimaryKey(t => t.PeopleID)
                .ForeignKey("dbo.Names", t => t.FirstNameID, cascadeDelete: true)
                .ForeignKey("dbo.Names", t => t.LastNameID, cascadeDelete: true)
                .ForeignKey("dbo.Names", t => t.MiddleNameID, cascadeDelete: true)
                .Index(t => t.FirstNameID)
                .Index(t => t.MiddleNameID)
                .Index(t => t.LastNameID);
        }
        public override void Down()
        {
            DropForeignKey("dbo.People", "MiddleNameID", "dbo.Names");
            DropForeignKey("dbo.People", "LastNameID", "dbo.Names");
            DropForeignKey("dbo.People", "FirstNameID", "dbo.Names");
            DropIndex("dbo.People", new[] { "LastNameID" });
            DropIndex("dbo.People", new[] { "MiddleNameID" });
            DropIndex("dbo.People", new[] { "FirstNameID" });
            DropIndex("dbo.Names", new[] { "Name" });
            DropTable("dbo.People");
            DropTable("dbo.Names");
        }
    }
}

我的目标是有一个"人员"表，其中所有 *NameID 都是名称表的外键。但是，只需要名字。当我第一次测试它时，我只有 FirstNameID 上的外键，它工作正常。但是当我将相同的内容复制/粘贴到其他名称时，这就是我现在所处的位置。

感谢任何和所有的帮助。谢谢。

Answer 1

级联删除只能通过流畅的配置关闭。但是，您尝试过的

modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();

没有效果，因为你没有many-to-many关系，而是3 one-to-many关系。相反，您应该单独配置每个关系：

modelBuilder.Entity<People>()
    .HasRequired(p => p.FirstName)
    .WithMany()
    .HasForeignKey(p => p.FirstNameID)
    .WillCascadeOnDelete(false);
modelBuilder.Entity<People>()
    .HasRequired(p => p.MiddleName)
    .WithMany()
    .HasForeignKey(p => p.MiddleNameID)
    .WillCascadeOnDelete(false);
modelBuilder.Entity<People>()
    .HasRequired(p => p.LastName)
    .WithMany()
    .HasForeignKey(p => p.LastNameID)
    .WillCascadeOnDelete(false);