如何使用实体框架代码优先从数据库中删除所有相关实体

Posted 2023-02-16

【中文标题】如何使用实体框架代码优先从数据库中删除所有相关实体

【英文标题】：How to delete all related entities from database with Entity Framework code-first

【发布时间】：2020-06-22 15:55:46

【问题描述】：

我在删除相关实体时遇到问题。例如，我需要从用户系列集合中删除其中一个系列。发生这种情况时，我希望删除数据库中与该系列记录相关的所有内容。怎么做？请提供示例，我有点卡住了。谢谢！

    public class User
    
        public Guid UserId  get; set; 
        public virtual List<Series> UserSeries  get; set; 
    

    public class DropPhoto
    
        public Guid DropPhotoId  get; set; 

        public virtual SimpleLine SimpleHorizontalLine  get; set; 
        public virtual SimpleLine SimpleVerticalLine  get; set; 
        public virtual Drop Drop  get; set; 
    

    public class ReferencePhoto
    
        public Guid ReferencePhotoId  get; set; 
        public virtual SimpleLine SimpleLine  get; set; 
    

    public class Series
    
        public Guid SeriesId  get; set; 
        public virtual List<DropPhoto> DropPhotosSeries  get; set; 
        public virtual ReferencePhoto ReferencePhotoForSeries  get; set;           
    

    public class SimpleLine
    
        public Guid SimpleLineId  get; set; 
    

public class Drop

    public Guid DropId  get; set; 

【参考方案1】：

您实际上是在寻找级联删除。

详情请看https://www.entityframeworktutorial.net/code-first/cascade-delete-in-code-first.aspx

这是一个例子

    public class Student

    public int StudentId  get; set; 
    public string StudentName  get; set; 

    public virtual StudentAddress Address  get; set; 


public class StudentAddress 

    [ForeignKey("Student")]
    public int StudentAddressId  get; set; 
    public string Address1  get; set; 
    public string Address2  get; set; 
    public string City  get; set; 
    public int Zipcode  get; set; 
    public string State  get; set; 
    public string Country  get; set; 

    public virtual Student Student  get; set; 

以下示例演示级联删除操作

using (var ctx = new SchoolContext()) 

    var stud = new Student()  StudentName = "James" ;
    var add = new StudentAddress()  Address1 = "address" ;

    stud.Address = add;

    ctx.Students.Add(stud);

    ctx.SaveChanges();

    ctx.Students.Remove(stud);// student and its address will be removed from db

    ctx.SaveChanges();