实体框架和外键:( [英] Having serious problems with Entity Framework & Foreign Keys :(

问题描述

我的EDMX中有以下实体： -

这两个内容是由更新模型从数据库生成的。

现在，注意我的国家/地区具有以下主键： -

名称& IsoCode

这是因为系统中的每个国家都是UNIQUE，由Name和IsoCode组成。

现在，我的国家...这是相似的。主键是： -

名称& CountryId

每个州名称和国家/地区都是唯一的。

国家的外键是国家。这是sql： -

  ALTER TABLE [dbo]。[States] WITH CHECK ADD 
 CONSTRAINT [FK_States_Countries] FOREIGN KEY（[CountryId]）
参考文献[dbo]。[Countries]（[CountryId]）
更新CASCADE 
 GO 
 
 ALTER TABLE [dbo]。 [状态]检查约束[FK_States_Countries] 
 GO 
  

很简单的东西。

但是EntityFramework不喜欢它:(假设我需要将一些属性从 State 实体连接到主键属性在国家/地区实体中。

是否可以在国家/地区之间添加一个协会。 CountryId< - > State.CountryId ...像我已经映射到我的数据库？

干杯;）

解决方案

在EF（3.5和4.0）中，FK必须指向主键。

但是你似乎是试图指出候选关键字（即[国家]] [我知道这是EF团队正在考虑的下一个版本，但是：）

希望这有助于

Alex

I've got the following entities on my EDMX :-

These two entites were generated by Update Model From Database.

Now, notice how my country has the following primary key :-

Name & IsoCode

this is because each country is UNIQUE in the system by Name and IsoCode.

Now, with my States ... it's similar. Primary Key is :-

Name & CountryId

Each state is unique by name and per country.

Now, the Foreign Key for States is a CountryId. This is the sql :-

ALTER TABLE [dbo].[States]  WITH CHECK ADD 
        CONSTRAINT [FK_States_Countries] FOREIGN KEY([CountryId])
REFERENCES [dbo].[Countries] ([CountryId])
ON UPDATE CASCADE
GO

ALTER TABLE [dbo].[States] CHECK CONSTRAINT [FK_States_Countries]
GO

Pretty simple stuff.

BUT EntityFramework doesn't like it :( It's assuming that i need to connect some properties from State entity to both primary key properties in the Country entity.

Is it possible to add an ASSOCIATION between Country and State on Country.CountryId <-> State.CountryId ... like i have mapped in my DB ?

Cheers ;)

解决方案

In EF (3.5 and 4.0) FKs MUST point to Primary Keys.

But you appear to be attempting to point to a Candidate Key (i.e. [Countries].[CountryId]

I know that this is something the EF team are considering for the next version though :)

Hope this helps

Alex

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