Problem getting values from checkedlist boxes vb.net 2022-CodePudding

I am trying to have a checkedlist box with values loaded at run time. But when I try to get checked values from it. it returns the following error:

Operator '&' is not defined for string '' and type 'DataRowView',

Though when I load the checkedlistbox at desigh it works fine

Public Sub loadListBox(ByVal lst As CheckedListBox, ByVal sql As String, ByVal fldDsp As String, ByVal fldVal As String)
    Try
        'open DB Connection
        openConn()
        Dim lstDS As New DataTable
        Dim lstAD As SqlDataAdapter
        Dim cboCMD As New SqlCommand(sql, Qconn)
        lstAD = New SqlDataAdapter(sql, Qconn)
        lstAD.Fill(lstDS)
        lst.Items.Clear()
        lst.SelectedIndex = -1

        With lst
            .Items.Clear()
            .DataSource = Nothing
            .Text = fldDsp
            .DataSource = lstDS
            .ValueMember = fldVal
            .DisplayMember = fldDsp

        End With



    Catch ex As Exception
        msgError("ERROR:Failed Loading Values  "   ex.Message)
        Exit Sub
    Finally

        closeConn()
    End Try

End Sub

---on form load

   Dim symp As String = "SELECT distinct facility   FROM [eLab].[settings].[Locations]"

       
        frm.chk_locations.Items.Clear()
            loadListBox(frm.CheckedListBox1, symp, "facility", "facility")


    Public Function getCheckedItems(ByVal chk As CheckedListBox) As String
        Dim items As String = ""
        If chk.CheckedItems.Count > 0 Then
            items = "" & chk.CheckedItems(0) & ""
            'check if the checked items are more than 1
            If chk.CheckedItems.Count > 1 Then
                For i As Integer = 1 To chk.CheckedItems.Count - 1
                    items = items & "," & chk.CheckedItems(i) & ""
                Next
            End If
        End If
        Return items
    End Function

 Dim configlocation As String = getCheckedItems(frm.CheckedListBox1)
msgBox(configlocation)

what I was Expecting is LocationA,Location X (alls selected locations comma separated

CodePudding user response：

When you bind a DataTable to a control, the data comes from its DefaultView, which is type DataView, which is a list of DataRowView objects. That means that each item in the control is a DataRowView, so obviously every checked item is a DataRowView. If what you actually want is the text displayed for each item then you need to call the GetItemText method of the control. If what you want is a comma-delimited string containing the text of the check ed items, this is what you should do:

Dim items = String.Join(",",
                        chk.CheckedItems.
                            Cast(Of Object)().
                            Select(Function(item) chk.GetItemText(item)))

That uses LINQ to get a list of checked items, get the a list of the text of those items, then join that list into s ingle comma-delimited String.