vb.net - LINQ to Objects - 不包含？

Question

我有一个项目集合，每个项目都有一个关系集合。我有一个项目可以与之建立关系的组列表。

我可以找到所有具有特定关系的项目，但我现在想找到与我的任何组没有关系的所有项目。

我可以通过执行以下操作找到与任何组有关系的项目：

Dim groupIds as List(of Integer) = (From g In cmdbGroups Select g.ID).ToList
Dim haveGroup = (From item In items _
                 Where item.Relationships.Any(Function(r) groupIds.Contains(r.TargetID)) _
                 Select item).ToList

如何找到与任何组没有关系的所有项目？

Answer 1

您是否尝试过否定该Contains方法的结果？

Dim groupIds as List(of Integer) = (From g In cmdbGroups Select g.ID).ToList
Dim haveGroup = (From item In items _
                 Where item.Relationships.Any(Function(r) Not groupIds.Contains(r.TargetID)) _
                 Select item).ToList

Answer 2

我不太记得 VB，但是一个简单的“不”应该可以工作。

Dim groupIds as List(of Integer) = (From g In cmdbGroups Select g.ID).ToList
Dim haveGroup = (From item In items _
             Where Not item.Relationships.Any(Function(r) groupIds.Contains(r.TargetID)) _
             Select item).ToList

Answer 3

如果您haveGroup无论如何都要生成集合，那么您可以执行以下操作：

Dim groupIds as List(of Integer) = (From g In cmdbGroups Select g.ID).ToList

Dim haveGroup = (From item In items _
    Where item.Relationships.Any(Function(r) groupIds.Contains(r.TargetID)) _
    Select item).ToList

Dim haveNotGroup = items.Except(haveGroup).ToList

Answer 4

Dim notHasGroup = items.Except(haveGroup)

Answer 5

Dim listIds as List(of Integer) = (From g In cmdbGroups Select g.ID).ToList
Dim haveGroup = (From item In items _
    Where Not listIds.Contains(item.ID) 
    Select item.ID).ToList