Question

实体框架代码优先。

我正在尝试在表上实现级联删除但是收到错误

＆＃34;参数@objname不明确或声称@objtype（COLUMN）错误。＆＃34;

我有以下型号：

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，我希望用户有一个＆＃34; Sick＆＃34;那天，能够说出他/她的症状......

同样，这就是我在实施方面遇到的问题。当我删除＆＃34;疾病＆＃34;对于特定日期，我想要一个级联删除来删除＆＃34;症状＆＃34;

我遵循了以下SO问题：

Entity Framework (EF) Code First Cascade Delete for One-to-Zero-or-One relationship

并添加了以下代码：

protected override void OnModelCreating(DbModelBuilder modelBuilder) {

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

base.OnModelCreating(modelBuilder);
}

当我添加迁移来实现它时，它会生成以下代码：

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，当我做一个＆＃34; update-database＆＃34;我收到以下错误，我不明白如何解决..

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

任何人都可以建议我做错了吗？

由于

Answer 1

你的数据库还在吗？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

我认为你的问题存在于关系中...你如何配置这个表？您可以在这些类之间的关系中添加一个虚拟类，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，你应该为User类做同样的事情。

也许这可以解决ambiguos列名，显示在错误消息

中

实体框架代码优先 - 级联删除

2 个答案: