EF4:NavigationProperty and join:是错误还是功能? [英] EF4: NavigationProperty and join: is a bug or a feature?

问题描述

我想咨询一下我遇到的问题.我已经开始研究一个数据库非常困难的项目:数据库中的许多表没有主键或有多个PK，因此我无法为edmx中的所有实体添加正确的关联.但是，对于某些实体来说，这是有可能的，而我设法做到了.因此，我有两个相互关联的实体:Vulner和VulnerDescription.而且我有一个针对Vulner的坏"连接表，称为VulnerObjectTie(带有心理性的FK:VulnerObjectTie.Vulner = Vulner.Id)，我无法向其中添加正确的关联.因此，我决定添加以下LinqtoEntities查询:

I’d like to consult about a problem I have faced. I've started working on a project with a very difficult database: many tables in the DB don’t have primary keys or have multiple PKs, so I can't add correct associations for all entities in my edmx. However, for some entities it’s possible and I managed to do so. Thus, I have two entities with an association between them: Vulner and VulnerDescription. And I have a "bad" connection table for Vulners called VulnerObjectTie (with a mental FK: VulnerObjectTie.Vulner = Vulner.Id), which I can’t add correct associations to. So, I decided to do add the following LinqtoEntities query:

            var vulerIdList = from vulner in _businessModel.DataModel.VulverSet.Include("Descriptions")
                    join objectVulnerTie in _businessModel.DataModel.ObjectVulnerTieSet on vulner.Id equals objectVulnerTie.Vulner
                    where softwareId.Contains(objectVulnerTie.SecurityObject)
                    select vulner;

，其中描述是与VulnerDescription表关联的导航属性.该查询有效，但不会加载Descriptions属性.但是，如果删除联接运算符，则说明将正确加载.

where description is Navigation Property for an association with the VulnerDescription table. The query works, but it does not load the Descriptions property. However, if I remove the join operator, then Descriptions are loaded correctly.

此问题最明显的解决方案是将一个查询分为接下来的两个查询:

The most obvious solution for this problem is to divide one query into the next two queries:

            var vulerIdList = from vulner in _businessModel.DataModel.VulverSet
                    join objectVulnerTie in _businessModel.DataModel.ObjectVulnerTieSet on vulner.Id equals objectVulnerTie.Vulner
                    where softwareId.Contains(objectVulnerTie.SecurityObject)
                    select vulner.Id;

        var query = from vulner in _businessModel.DataModel.VulverSet.Include("Descriptions")
                    where vulerIdList.Contains(vulner.Id)
                    select vulner;

但我认为它看起来很丑.谁能为这个问题提出一个更简单的解决方案，还是仅仅是EF4的一项特殊功能?

But I think it looks ugly. Can anyone suggest a more simple solution for this problem, or is it just a special feature of EF4??

thankyouplease:))

thankyouplease :))

推荐答案

这是已知的功能"或局限性，具体取决于您如何看待它.这是一个有关该主题的有趣讨论，我敢肯定还有更多参考可以找到:

It's a known 'feature' or limitation, depending on how you look at it. Here's an interesting discussion on the topic, I'm sure there are more references to find: http://social.msdn.microsoft.com/forums/en-US/adodotnetentityframework/thread/d700becd-fb4e-40cd-a334-9b129344edc9/

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