Linq-过滤器列表

Question

我正在使用SQL Server数据库在vb.net Windows窗体应用程序中构建一个简单的搜索工具， 用户将输入一个唯一的ID，并将看到显示状态的结果。

对象类：

            Public Class IStatus
                    Public Property Id As String
                    Public Property Status As String

                    Public Sub New(ByVal Id As String, ByVal Status As String)
                        Id = Id
                        Status = Status            
                    End Sub
            End Class

我正在做的是在List（Of IStatus）中填充数据库中的行 现在，我想使用linq从数据表中过滤行，到目前为止，我已经完成了以下操作：

            Public Function GetDS() As List(Of IStatus)
                    Dim sRows As New List(Of IStatus)
                    Dim dr As SqlDataReader = GetDataReader()
                    If dr.HasRows Then
                        Using dt As New DataTable
                            dt.Load(dr)
                            totRows = dt.Rows.Count
                            If (totRows > 1) Then
                                For Each drow As DataRow In dt.Rows
                                    Dim sRow As New IStatus(drow(0).ToString(), drow(1).ToString())
                                    sRows.Add(sRow)
                                Next

                                'Trying to filter the data with linq conditions here ... 
                                Dim uniqRows = sRows.Where(Function(p) p.Status = "Open" Or p.Status = "Closed" Or p.Status = "Unknown").ToList
                                sRows = uniqRows.ToList
                            Else
                                Dim sRow As New IStatus(dt.Rows(0)(0).ToString, dt.Rows(0)(1).ToString)
                                sRows.Add(sRow)
                            End If
                            Return sRows
                        End Using
                    End If
            End Function

我有以下对象的列表：

IStatus
-----------
Id
Status

以下是我想要实现的示例数据和过滤：

例如数据：

-----------------
Id           Status
-----------------
1            Open
1            Open
1            Closed

返回所有行，因为状态值之一不同。

Id           Status
-----------------
1            Open
1            Open
1            Open

仅返回第一行，因为所有状态值都相同。

Id           Status
-----------------
1            Unknown
1            Open
1            Open

如果任一状态为“未知”，则返回“未知”行。

谢谢。

Answer 1

您可以使用findall函数来过滤通用列表

Public Class IStatus
    Public Property Id As String
    Public Property Status As String

    Public Sub New(ByVal Id_ As String, ByVal Status_ As String)
        Id = Id_
        Status = Status_
    End Sub
End Class
Function Createlist() As List(Of IStatus)
    Dim L1 = New List(Of IStatus)()
    L1.Add(New IStatus("1", "open"))
    L1.Add(New IStatus("1", "open"))
    L1.Add(New IStatus("1", "closed"))
    L1.Add(New IStatus("1", "closed"))
    L1.Add(New IStatus("1", "closed"))
    L1.Add(New IStatus("2", "open"))
    L1.Add(New IStatus("2", "open"))
    L1.Add(New IStatus("2", "closed"))
    L1.Add(New IStatus("2", "closed"))
    L1.Add(New IStatus("2", "closed"))
    Return L1
End Function
Sub main()
    Dim l1 = Createlist().FindAll(Function(x As IStatus) x.Id = "1")
    For Each ii In l1
        With ii
            Console.WriteLine(.Id & "- " & .Status)
        End With

    Next
    Stop
End Sub