Question

我有一个带有CheckedListBox的表单，用户可以在其中选择多个选项（它过滤目录文件列表 - 过滤后的文件出现在第二个列表框中）。

如果我有一定数量的选项，我可以在查询中使用“或”，如下所示：

Dim query = From f As System.IO.FileInfo In StartList
    Where f.Name.Contains("Romania")
Where f.Channel = "Channel1" Or f.Channel = "Channel2"

但是，由于此人可以点击任意数量的选项（或没有），我不能这样做。我尝试过几个方面，包括尝试创建多个子查询，然后对它们执行联盟，但我无法让它工作。

到目前为止，这是我的代码：

Dim Channels = ChannelListBox.CheckedItems

    Dim query = From f As System.IO.FileInfo In StartList
    Where f.Name.Contains("Romania")

    If Channels.Count > 0 Then

        Dim CurrentName As String = Channels(0).ToString

        Dim Subquery = From g As System.IO.FileInfo In query
                Where (g.Name.Contains(CurrentName))

        For i = 1 To Channels.Count - 1

            CurrentName = Channels(i).ToString
            Dim Subquery2 = From h As System.IO.FileInfo In query
                                Where (h.Name.Contains(CurrentName))

            Subquery = Subquery.Union(Subquery2)

        Next i

        FileListBox.DataSource = Subquery.ToList

    Else

        FileListBox.DataSource = query.ToList

    End If

感谢您的帮助，安德鲁

Answer 1

Dim Channels = ChannelListBox.CheckedItems
Dim ChannelNames = From c.ToString In Channels
Dim query = From f As System.IO.FileInfo In StartList
    Where f.Name.Contains("Romania") And ChannelNames.Any(Function(n) f.Name.Contains(n))

我没有VB.NET经验，更不用说LINQ了，所以我希望我的语法是正确的。这是我在C＃中写的内容：

var channels = ChannelListBox.CheckedItems;
var channelNames = channels.Select(c => c.ToString());
var query = from f in StartList.Cast<System.IO.FileInfo>()
    where f.Name.Contains("Romania") && channelNames.Any(n => f.Name.Contains(n))
    select f;

在LINQ条件查询中使用“Or”

1 个答案: