实体框架核心级联删除一对多关系 [英] Entity Framework Core cascade delete one to many relationship

问题描述

public class Station : IEntitie
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    public virtual ICollection<RegulatorySchedule> RegulatoryScheduleDispatchStations { get; set; }    

    public virtual ICollection<RegulatorySchedule> RegulatoryScheduleDestinationStations { get; set; }   
}

public class RegulatorySchedule : IEntitie
{
    [Key]
    public int Id { get; set; }

    public virtual Station DispatchStation { get; set; }      

    public virtual Station DestinationStation { get; set; }     
}


protected override void OnModelCreating(ModelBuilder modelBuilder)
{
        modelBuilder.Entity<RegulatorySchedule>()
            .HasOne(s => s.DestinationStation)
            .WithMany(s => s.RegulatoryScheduleDestinationStations)
            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);

        modelBuilder.Entity<RegulatorySchedule>()
            .HasOne(s => s.DispatchStation)
            .WithMany(s => s.RegulatoryScheduleDispatchStations)
            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);
}

只有在删除限制
OnDelete（Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict）。
否则，它将引发异常：

The database is created during migration only when I clearly expose the behavior when deleting Restrict OnDelete (Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict). Otherwise, it throws an exception:

在表$ b $上引入FOREIGN KEY约束
'FK_RegulatorySchedules_Stations_DispatchStationId' b'RegulatorySchedules'可能会导致循环或多个级联路径。
指定ON DELETE NO ACTION或ON UPDATE NO ACTION，或修改其他
FOREIGN KEY约束。

"Introducing FOREIGN KEY constraint 'FK_RegulatorySchedules_Stations_DispatchStationId' on table 'RegulatorySchedules' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints."

我需要删除表的Station Station和与表相关的属性RegulatorySchedules DispatchStation和DestinationStation暴露为NULL。
但是Restrict选项在删除无法放下的SetNull时会有例外。
告诉我怎么做？

I need the removal of the Station Stations of the table and the table-related properties RegulatorySchedules DispatchStation and DestinationStation exposed to NULL. But Restrict option there is an exception when you delete a SetNull I can not put. Tell me how to be?

推荐答案

描述的问题与实体框架无关-这是对MS SQL Server本身。具有多个FK的表可能只有其中一个具有 cascade 删除。

Described "problem" is not related to Entity Framework - this is restriction of MS SQL Server itself. Table with several FKs may have only one of them with cascade delete.

因此，一旦您需要两个FK都具有级联-您应该在代码中实现此类清理。将一个（或两个）FK设置为​​ DeleteBehavior.Restrict ，并在控制器/服务中，然后手动删除 Station 并删除所有相关的 RegulatorySchedule

So, as soon as you need both FKs to have cascade - you should implement such "cleanup" in your code. Set one (or both) FKs to DeleteBehavior.Restrict, and in your controller/service prior to removing Station manually find and delete all related RegulatorySchedule

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