Question

我有一个获取对象列表的方法在持久化对象之前，我必须在某些特定情况下删除它们中的一些

例如（不是理想的！）：

公司可以拥有Id和分支列表以及IsDeleted标志   分支可以有一个Id和一个Managers列表以及一个IsDeleted标志
  经理可以拥有Id和IsDeleted标志   公司 - ＆gt;分行 - ＆gt;经理

什么是简单或最好的过滤方式，以省略Id = 0和IsDeleted = True的组合，以便我可以迭代并执行具体操作 - 请参阅下面的函数

如果公司被标记为Id = 0 and IsDeleted，那么我想完全省略
但如果只将分支标记为Id=0 and Isdeleted，那么公司应该没有分支
如果只有经理被列为Id=0 and Isdeleted，那么公司和分公司应该在那里

Private Function(comp as List(Of Company)) as Boolean
    'filter comp here and pass it to for loop??
    Dim filteredList as ...
    For each c as Company in filteredList 
    'do company specifis here
        For each b as Branch in c.Branches
        'do branch specific here
            For Each m as Manager in b.Managers
            'do manager specific here
            Next
        Next
    Save(c) ' saves child objects as well    
    Next
End Function

Answer 1

你可以使用Linq：

Dim filtered = From c In comp Where Not c.IsDeleted OrElse c.Id <> 0
             From b In c.Branches Where Not b.IsDeleted OrElse b.Id <> 0
             From m In b.Managers Where Not m.IsDeleted OrElse m.Id <> 0
             Select New With {.Company = c, .Branch = b, .Manager = m}

For Each x In filtered
    Dim c As Company = x.Company
    Dim b As Branch = x.Branch
    Dim m As Manager = x.Manager
Next

或者，如果您想分别枚举每种类型：

Dim filteredComp = From c In comp Where Not c.IsDeleted OrElse c.Id <> 0
Dim filteredBranch = From c In filteredComp
                   From b In c.Branches Where Not b.IsDeleted OrElse b.Id <> 0
                   Select b
Dim filteredManager = From b In filteredBranch
                   From m In b.Managers Where Not m.IsDeleted OrElse m.Id <> 0
                   Select m

For Each c In filteredComp

Next
For Each b In filteredBranch

Next
For Each m In filteredManager

Next

Answer 2

这会解决您的问题吗？

Dim filtererdComp = comp _
    .Where(Function(c) c.Id<>0 Or Not c.IsDeleted)
    .ToList()
For each c as Company in filtererdComp
    c.Branches = c.Branches _
        .Where(Function(b) b.Id<>0 Or Not b.IsDeleted) _
        .ToList()
    For each b As Branch in c.Branches
        b.Managers = b.Managers _
            .Where(Function(m) m.Id<>0 Or Not m.IsDeleted) _
            .ToList()
    Next
Next

Answer 3

在迭代的每个级别中，循环遍历该级别上的所有现有元素。使用if语句检查ID = 0和IsDeleted是否为true，在这种情况下删除该条目。

过滤或从列表中删除（Of T）

3 个答案: