实体框架代码优先-级联删除

Question

实体框架代码优先。

我正在尝试在表上实现级联删除，但出现错误

“参数@objname模棱两可，或者声明的@objtype（COLUMN）错误。”

我有以下模型：

用户表：

public class User {
    public int id { get; set; }
    public List<UserSickness> Sickness { get; set; }
}

疾病表：

public class UserSickness {
    public int id { get; set; }
    public DateTime SicknessDate { get; set; }
    public List<Symptom> Symptoms { get; set; }
}

症状表：

public class Symptom {
    public int id { get; set; }
    public string Description { get; set; }
}

所以，基本上，我希望用户度过一个“病假”的日子，并能够说出他/她的症状是什么...

同样，这就是我在实施时遇到的问题。 当我删除特定日期的“疾病”时，我希望通过级联删除来删除“症状”

我遵循以下SO问题：

一对一或一对一关系的实体框架（EF）代码优先级联删除

并添加以下代码：

protected override void OnModelCreating(DbModelBuilder modelBuilder) {

// delete symptoms
modelBuilder.Entity<DatapultData.Model.UserSickness>()
.HasOptional(a => a.Symptoms)
.WithOptionalDependent()
.WillCascadeOnDelete(true);

base.OnModelCreating(modelBuilder);
}

当我添加迁移以实现此功能时，它将生成以下代码：

namespace Data.Migrations
{
using System;
using System.Data.Entity.Migrations;

public partial class addedcascadingdeleteonsymptoms : DbMigration
{
    public override void Up()
    {
        DropForeignKey("dbo.Symptoms", "UserSickness_id", "dbo.UserSicknesses");
        DropIndex("dbo.Symptoms", new[] { "UserSickness_id" });
        RenameColumn(table: "dbo.UserSicknesses", name: "UserSickness_id", newName: "Symptoms_id");
        CreateIndex("dbo.UserSicknesses", "Symptoms_id");
        AddForeignKey("dbo.UserSicknesses", "Symptoms_id", "dbo.Symptoms", "id", cascadeDelete: true);
        DropColumn("dbo.Symptoms", "UserSickness_id");
    }

    public override void Down()
    {
        AddColumn("dbo.Symptoms", "UserSickness_id", c => c.Int());
        DropForeignKey("dbo.UserSicknesses", "Symptoms_id", "dbo.Symptoms");
        DropIndex("dbo.UserSicknesses", new[] { "Symptoms_id" });
        RenameColumn(table: "dbo.UserSicknesses", name: "Symptoms_id", newName: "UserSickness_id");
        CreateIndex("dbo.Symptoms", "UserSickness_id");
        AddForeignKey("dbo.Symptoms", "UserSickness_id", "dbo.UserSicknesses", "id");
    }
}

}

但是，当我执行“更新数据库”时，出现以下错误，我不知道如何解决。

Either the parameter @objname is ambiguous or the claimed @objtype (COLUMN) is wrong.

谁能暗示我在做什么错？

谢谢

Answer 1

您的数据库还在吗？ 如果删除数据库，则会发生这种情况。 如果未删除，请尝试删除迁移脚本，添加迁移（通过NuGet）并更新数据库。

Answer 2

我认为您的问题出在关系中...如何配置此表？ 您可以将虚拟类添加到此类之间的关系，例如导航属性

public class UserSickness {
    public int id { get; set; }
    public DateTime SicknessDate { get; set; }
    public List<Symptom> Symptoms { get; set; }

    // Navigation property
    public virtual User UserAsociated { get; set; }
}

public class Symptom {
    public int id { get; set; }
    public string Description { get; set; }

    // Navigation property
    public virtual UserSickness UserSicknessAsociated { get; set; }
}

然后，将配置更改为

protected override void OnModelCreating(DbModelBuilder modelBuilder) {

// delete symptoms
modelBuilder.Entity<DatapultData.Model.UserSickness>()
.HasOptional(a => a.Symptoms)
.WithRequired(b => b.UserSicknessAsociated)//Update this line
.WillCascadeOnDelete(true);

base.OnModelCreating(modelBuilder);
}

为了避免类似的错误，您应该对User类进行相同的设置。

也许这可以解决错误消息中显示的歧义列名称