如何在LINQ Where子句中搜索集合的集合？

Question

我有以下ADO.NET实体框架实体数据模型:

我想找到具有给定Id的服务和给定状态的关键字的所有保单持有人.

这个LINQ不起作用:

Dim ServicesId As Integer = ...
Dim KeywordStatus As Integer = ...

Dim FoundPolicyholders = From p As Policyholder In db.PolicyholderSet.Include("Keywords").Include("Services") _
                         Where p.Services.Id = ServicesId _
                         And p.Keywords.Status = KeywordStatus _
                         Select p

Where子句不能以这种方式搜索p.Services和p.Keywords EntityCollections.

'Id'不是'System.Data.Objects.DataClasses.EntityCollection(Of .... Service)'的成员.

什么是正确的LINQ语法来做我想要的？

Answer 1

db.PolicyholderSet.Where(ph =>
   ph.Services.Any(s => s.Id == someId) &&
   ph.Keywords.Any(kw => kw.Status == someStatus))

为什么你的查询不起作用？因为p.Services并且p.Keywords是一个Service和一个Keyword集合 - 他们没有财产Id或Status因此你不能使用p.Services.Id或p.Keywords.Status.

Visual Basic ......

Dim FoundPolicyholders = From p As Policyholder In db.PolicyholderSet.Include("Keywords").Include("Services") _
                         Where p.Services.Any(Function(s) s.Id = ServicesId) _
                         And p.Keywords.Any(Function(k) k.Status = KeywordStatus) _
                         Select p