实体框架层次结构的代码优先映射 [英] Code First Mapping for Entity Framework Hierarchy
问题描述
我有一个如下所示的模型:
public class Category
{
public string Id {get;组; }
public string描述{get;组; }
public Category Parent {get;组; }
public ICollection< Category>孩子{get;组; }
public ICollection< Product>产品{get;组;
}
一个数据库表看起来像
类别
Id(PK varchar(5))
描述(nvarchar(50))
ParentId(FK varchar ))
但是,在设置映射时,Im被拒绝
modelBuilder.Entity< Category>()
.HasMany(x => x.Children)
.WithMany(x => x.Children)
.Map(m =>
{
m.ToTable(Categories);
m.MapLeftKey(x => x.Id, Id);
m.MapRightKey(x => x.Id,ParentId);
});
我可以看到为什么映射失败(StackOverflowException),但不确定如何解决它。任何帮助都会非常感激。
这是使用最新版本的EF(4.1?)。
谢谢!
为什么在相同的导航属性上映射多对多关系?这是完全错误的。首先,你的表格显然期待一对多关系。即使您需要多对多关系,您也不能使用相同的导航属性。
只需尝试:
$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ b $
.Map(m => m.MapKey(ParentId));
I have a model that looks like this:
public class Category
{
public string Id { get; set; }
public string Description { get; set; }
public Category Parent { get; set; }
public ICollection<Category> Children { get; set; }
public ICollection<Product> Products { get; set; }
}
With a database table that looks like
Categories
Id (PK varchar(5))
Description (nvarchar(50))
ParentId (FK varchar(5))
But Im stumped when it comes to setting up the mapping
modelBuilder.Entity<Category>()
.HasMany(x => x.Children)
.WithMany(x => x.Children)
.Map(m =>
{
m.ToTable("Categories");
m.MapLeftKey(x => x.Id, "Id");
m.MapRightKey(x => x.Id, "ParentId");
});
I can see why the mapping fails (StackOverflowException), but am unsure as to how to fix it. Any help would be greately appreciated.
This is using the latest release of EF (4.1?).
Thanks!
Why do you map many-to-many relation on the same navigation property? That is completely wrong. First your table obviously expect one-to-many relation. Even if you need many-to-many relation you cannot use the same navigation property for that.
Just try:
modelBuilder.Entity<Category>()
.HasMany(x => x.Children)
.WithOptional(y => y.Parent)
.Map(m => m.MapKey("ParentId"));
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