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[英]EntityFramework CodeFirst: CASCADE DELETE for same table many-to-many relationship
[英]Delete on cascade many-to-many relationship on EF
如圖所示,您只有兩個桌子。 不可能將它們之間的關系設置為多對多(僅當您將在出現新對時在此表中添加新列,但這是非常不好的做法)。 您應該創建第三個表,該表將包含成對的主鍵。 並且在遷移時,您將能夠在每個主表與第三個主表之間將cascadeDelete指定為true。 見下文:
楷模:
public class BugReport
{
public BugReport()
{
dublicates = new HashSet<DublicateBugReport>();
}
public int ID { get; set; }
public virtual ICollection<DublicateBugReport> dublicates { get; set; }
}
public class DublicateBugReport
{
public DublicateBugReport()
{
reports = new HashSet<BugReport>();
}
public int ID { get; set; }
public virtual ICollection<BugReport> reports { get; set; }
}
遷移的一部分:
public override void Up()
{
CreateTable(
"BugReports",
c => new
{
ID = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.ID) ;
CreateTable(
"DublicateBugReports",
c => new
{
ID = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.ID) ;
CreateTable(
"DublicateBugReportBugReports",
c => new
{
DublicateBugReport_ID = c.Int(nullable: false),
BugReport_ID = c.Int(nullable: false),
})
.PrimaryKey(t => new { t.DublicateBugReport_ID, t.BugReport_ID })
//pay attention! - cascadeDelete: true
.ForeignKey("DublicateBugReports", t => t.DublicateBugReport_ID, cascadeDelete: true)
.ForeignKey("BugReports", t => t.BugReport_ID, cascadeDelete: true)
.Index(t => t.DublicateBugReport_ID)
.Index(t => t.BugReport_ID);
}
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