[英]EF Code First, two navigation properties to same object
我正在使用EF Code First来查询和创建数据库。 我的一个实体(关系)具有两个到同一实体(活动)的导航属性。 我的问题是,如果我使用EF来创建数据库模式,它将创建四个外键列和约束而不是两个。
以下是相关的代码部分:
活动类:
public class Activity {
public virtual ICollection<Relationship> Successors { get; set; }
public virtual ICollection<Relationship> Predecessors { get; set; }
}
关系类:
public class Relationship {
public virtual Activity Activity1 { get; set; }
public int Activity1_ID { get; set; }
public virtual Activity Activity2 { get; set; }
public int Activity2_ID { get; set; }
}
关系映射类:
this.HasRequired(t => t.Activity1)
.WithMany(t => t.Predecessors)
.HasForeignKey(m => m.Activity1_ID)
.WillCascadeOnDelete(false);
this.HasRequired(t => t.Activity2)
.WithMany(t => t.Successors)
.HasForeignKey(m => m.Activity2_ID)
.WillCascadeOnDelete(false);
有没有办法阻止创建最后两列?
这应该只创建2个外键列。
public class Activity
{
public int Id { set; get; }
public virtual ICollection<Relationship> Successors { get; set; }
public virtual ICollection<Relationship> Predecessors { get; set; }
}
public class Relationship
{
public int Id { set; get; }
public virtual Activity Activity1 { get; set; }
public int Activity1_ID { get; set; }
public virtual Activity Activity2 { get; set; }
public int Activity2_ID { get; set; }
}
我所在的地方,指定我的关系/ FK性质的DbContext类OnModelCreating
。
public class MyDb: DbContext
{
public MyDb():base("EfDbContext")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Relationship>()
.HasRequired(f => f.Activity1)
.WithMany(f => f.Predecessors)
.HasForeignKey(g => g.Activity1_ID)
.WillCascadeOnDelete(false);
modelBuilder.Entity<Relationship>().
HasRequired(f => f.Activity2)
.WithMany(f => f.Successors)
.HasForeignKey(g => g.Activity2_ID)
.WillCascadeOnDelete(false);
}
}
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