EF 코드 첫 번째 데이터베이스에서 자식 일대 다 관련 레코드를 제거하는 방법은 무엇입니까?

EF 코드 첫 번째 데이터베이스에서 자식 일대 다 관련 레코드를 제거하는 방법은 무엇입니까?

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음, 일대 다 관련 모델이 있습니다.

public class Parent
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Child> Children { get; set; }
}

public class Child
{
    public int Id { get; set; }
    public string ChildName { get; set; }
}

내가 원하는 것은 Parent.Children데이터베이스에서 관련 하위 엔티티를 지우고 제거하는 것입니다. 나는 이미 시도했다 :

데이터베이스 컨텍스트 클래스 :

modelBuilder.Entity<Parent>()
            .HasMany(p => p.Children)
            .WithOptional()
            .WillCascadeOnDelete(true);

이것은 잘 작동하지만 Parent_Id = null할 때 필드가 있는 데이터베이스에 중복 레코드 가 있습니다.

parent.Children.Clear();
repository.InsertOrUpdate(parent);

내 저장소 클래스에서. 또한 동일한 동작은 다음과 같습니다.

modelBuilder.Entity<Parent>()
            .HasMany(pr => pr.Children)
            .WithOptional(ri => ri.Parent)
            .WillCascadeOnDelete(true);

클래스의 추가 Parent속성Child

public class Child
{
    ...
    public Parent Parent { get; set; }
    ...
}

또는 내가 할 때

modelBuilder.Entity<Child>()
            .HasOptional(p => p.Parent)
            .WithMany(p => p.Children)
            .HasForeignKey(p => p.Parent_Id)
            .WillCascadeOnDelete(true);

Child클래스에 추가 Parent_Id 속성 포함

public class Child
{
     ...
     public int Parent_Id { get; set; }
     ...
}

그렇다면 계단식 삭제를 올바르게 구성하려면 어떻게해야합니까? 또는 해당 하위 엔티티를 어떻게 제거해야합니까? 나는 이것이 평범한 일이라고 생각하지만 나는 단지 무언가를 놓치고 있습니다.

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Cascading delete has no effect here because you don't delete the parent but just call InsertOrUpdate. The correct procedure is to delete the children one-by-one, like so for example:

using (var context = new MyContext())
{
    var parent = context.Parents.Include(p => p.Children)
        .SingleOrDefault(p => p.Id == parentId);

    foreach (var child in parent.Children.ToList())
        context.Children.Remove(child);

    context.SaveChanges();
}

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In EF6 a faster way to do the operation is...

 context.Children.RemoveRange(parent.Children)

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This is called "deleting orphans".

Can EF automatically delete data that is orphaned, where the parent is not deleted?

I don't know how it works in EF6 but in EF Core it works fine https://docs.microsoft.com/en-us/ef/core/saving/cascade-delete so you don't necessarily need to delete the parent for cascades to work.

Delete orphans examples

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Try changing to

 public virtual ICollection<Child> Children { get; set; }

because virtual is needed to get lazy loading. as explained here

I think your parent.Children.clear isnt working because the Children have not been loaded

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If your object is self-referencing, you can delete both many-to-many and one-to-many children using the method below. Just remember to call db.SaveChanges() afterwards :)

[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public ActionResult DeleteConfirmed(int id)
{
    Object obj = this.db.Objects.Find(id);
    this.DeleteObjectAndChildren(obj);
    this.db.Objects.Remove(obj);
    this.db.SaveChanges();
    return this.Json(new { success = true });
}

/// <summary>
/// This deletes an object and all children, but does not commit changes to the db.
///  - MH @ 2016/08/15 14:42
/// </summary>
/// <param name="parent">
/// The object.
/// </param>
private void DeleteObjectAndChildren(Object parent)
{
    // Deletes One-to-Many Children
    if (parent.Things != null && parent.Things.Count > 0)
    {
        this.db.Things.RemoveRange(parent.Things);
    }

    // Deletes Self Referenced Children
    if (parent.Children != null && parent.Children.Count > 0)
    {
        foreach (var child in parent.Children)
        {
            this.DeleteObjectAndChildren(child);
        }

        this.db.Objects.RemoveRange(parent.Children);
    }
}

참고URL : https://stackoverflow.com/questions/16654828/how-to-remove-child-one-to-many-related-records-in-ef-code-first-database