Question

我觉得这个功能太长了。我可以将它分成两个函数，但我更愿意将它们保存在一个函数中。

Public Function getTempList(ByVal applicationType As String) As List(Of String)
    Dim doc As XDocument = New XDocument


    If My.Settings.sortKey = "alpha" Then
        Dim XMLquery = From c In doc.<applications>.<app> _
           Where c.<appFav>.Value = "true" And c.<appType>.Value = applicationType
           Order By CStr(c.<appName>.Value)
           Select c.<appName>
        Dim tempList As New List(Of String)
        For Each result In XMLquery
            tempList.Add(result.Value)
        Next
        Return tempList
    ElseIf My.Settings.sortKey = "fav" Then ' ------------------------------------------------------------------------------------ 
        Dim XMLquery = From c In doc.<applications>.<app> _
           Where c.<appFav>.Value = "true" And c.<appType>.Value = applicationType
           Order By CInt(c.<appClick>.Value) Descending
           Select c.<appName>
        Dim tempList As New List(Of String)
        For Each result In XMLquery
            tempList.Add(result.Value)
        Next
        Return tempList
    End If

End Function

我可以以某种方式将if语句放在LINQ查询本身中。这里唯一需要改变的是列表所在的顺序。或者，是否有其他方式来订购我要返回的结果？

Answer 1

试试这个，

 Public Function getTempList(ByVal applicationType As String) As List(Of String)
        Dim doc As XDocument = New XDocument
        Dim XMLquery = From c In doc.<applications>.<app> _
              Where c.<appFav>.Value = "true" And c.<appType>.Value = applicationType
              Select c
        Dim tempList As New List(Of String)

        If My.Settings.sortKey = "alpha" Then

            XMLquery = XMLquery.OrderBy(Function(c) CStr(c.<appName>.Value))

        ElseIf My.Settings.sortKey = "fav" Then

            XMLquery = XMLquery.OrderByDescending(Function(c) CInt(c.<appClick>.Value))

        End If

        For Each result In XMLquery
            tempList.Add(result.<appName>.Value)
        Next
        Return tempList
    End Function

Answer 2

我认为这是最简单的：

Public Function getTempList(ByVal applicationType As String) As List(Of String)

    Dim doc As XDocument = New XDocument

    Dim XMLquery = _
        From c In doc.<applications>.<app> _
        Where c.<appFav>.Value = "true" And c.<appType>.Value = applicationType _
        Select c

    If My.Settings.sortKey = "alpha" Then
        XMLquery = XMLquery.OrderBy(Function(c) CStr(c.<appName>.Value))
    ElseIf My.Settings.sortKey = "fav" Then
        XMLquery = XMLquery.OrderByDescending(Function(c) CInt(c.<appClick>.Value))
    End If

    Return XMLquery.Select(Function(x) x.<appName>.Value).ToList()

End Function

Answer 3

您无需重复整个查询。

您可以执行以下操作：

请原谅我的VB语法，我通常用C＃编写代码。

Public Function getTempList(ByVal applicationType As String) As List(Of String)
    Dim doc As XDocument = New XDocument
    Dim tempList As New List(Of String)

    Dim XMLquery = From c In doc.<applications>.<app> _
       Where c.<appFav>.Value = "true" And c.<appType>.Value = applicationType
       Select c.<appName>

    If My.Settings.sortKey = "aplha" Then
        Order XMLQuery By CStr(c.<appName>.Value)   // convert to VB code

    If My.Settings.sortKey = "fav" Then
        Order XMLQuery By CInt(c.<appClick>.Value) Descending //convert to VB code

    For Each result In XMLquery
        tempList.Add(result.Value)
    Next

    Return tempList
End Function

你能在LINQ（XML）查询中添加一个If语句吗？

3 个答案: