EF4 CTP5自引用分层实体映射 [英] EF4 CTP5 self-referencing hierarchical entity mapping

问题描述

好的，这应该很容易，但是我一直在梳理头发.这是我的POCO(与机器零件有关，因此零件可以包含在父零件中):

Okay, this should be really easy, but I've been tearing my hair out. Here's my POCO (which has to do with machine parts, so a part can be contained within a parent part):

public class Part
{
   public int ID { get; set; }
   public string Name { get; set; }
   public Part ParentPart { get; set; }
}

创建数据库表时，列名称为"ID"，名称"和"PartID".如何将最后一列的名称更改为"ParentPartID"?

When the database table is created, the column names are "ID", "Name", and "PartID". How do I change the name of that last column to "ParentPartID"?

推荐答案

基本上，您想在 Independent Association 中重命名外键，这是可以做到这一点的流畅的API代码:

Basically, you want to rename the foreign key in an Independent Association and this is the fluent API code that will do it:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Part>()
                .HasOptional(p => p.ParentPart)
                .WithMany()
                .IsIndependent()
                .Map(m => m.MapKey(p => p.ID, "ParentPartID"));
}

但是，由于CTP5中的错误，此代码在自引用关联(这是您的关联类型)中作为异常抛出.解决方法是将您的关联更改为外键关联，如下所示:

However, due to a bug in CTP5, this code throw as exception in self referencing associations (which is your association type). The workaround would be to change your association to a Foreign Key Association as follows:

public class Part
{
    public int ID { get; set; }
    public string Name { get; set; }                
    public int ParentPartID { get; set; }

    [ForeignKey("ParentPartID")]
    public Part ParentPart { get; set; }
}

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