全局禁用EF Core 2上的级联删除 [英] Disable cascade delete on EF Core 2 globally

问题描述

我需要了解全局禁用 EF Core 2 的级联删除的方法。

I need to know about ways of disabling cascade delete in EF Core 2 globally. Any help is appricated.

在EF 6.x中，我们使用以下代码在 OneToMany 和$ ManyToMany 场景：

In EF 6.x we used following code to disable cascade delete on both OneToMany and ManyToMany realtions:

builder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
builder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();

推荐答案

不幸的是，目前是EF Core（当前v2。 0）并没有提供一种全局控制约定的好方法。

Unfortunately EF Core currently (latest at this time v2.0) does not expose a good way to control the conventions globally.

默认的EF Core 2.0约定是使用 DeleteBehavior.Cascade 表示必需关系， DeleteBehavior.ClientSetNull 表示可选关系。我可以建议作为解决方法的是在 OnModelCreating 覆盖结尾处的典型元数据模型循环。在这种情况下，找到所有已发现的关系并进行相应的修改：

The default EF Core 2.0 convention is to use DeleteBehavior.Cascade for required and DeleteBehavior.ClientSetNull for optional relationships. What I can suggest as workaround is a typical metadata model loop at the end of the OnModelCreating override. In this case, locating all the already discovered relationships and modifying them accordingly:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    // ...

    var cascadeFKs = modelBuilder.Model.GetEntityTypes()
        .SelectMany(t => t.GetForeignKeys())
        .Where(fk => !fk.IsOwnership && fk.DeleteBehavior == DeleteBehavior.Cascade);

    foreach (var fk in cascadeFKs)
        fk.DeleteBehavior = DeleteBehavior.Restrict;

    base.OnModelCreating(modelBuilder);
}

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