如何使用實體框架代碼優先從數據庫中刪除所有相關實體

Question

我在刪除相關實體時遇到問題。 例如，我需要從用戶系列集合中刪除系列之一。 發生這種情況時，我希望刪除數據庫中與此系列記錄相關的所有內容。 怎么做？ 請提供示例，我有點卡住了。 謝謝！

    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; }
}

Answer 1

您實際上是在尋找級聯刪除。

詳情請看https://www.entityframeworktutorial.net/code-first/cascade-delete-in-code-first.aspx

這是一個例子

    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; }
}

下面的例子演示了級聯刪除操作

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();
}