.NET ListView Control Export To CSV File

I love the listview - low resource requirement, reasonably fast and I have built some utilities to ease the workload.

I am often asked by the users for an export of the grid data. This would normally require that I keep the table used to populate the listview in memory and then to format the table to reflect the listview data.

This assumes that you use a generic table with ids and keys and other extraneous bits and pieces which you then hide from the user by making the column width = to 0. If you are one of these people who design the servicing table to fit the exact requirements of the listview then more joy to you, this will be of limited use.

The other assumption is that you store the ID for the record in the tag property of the listviewitem.

The call from a menu item to export the data

Private Sub ExportGridToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExportGridToolStripMenuItem.Click
Dim sMsg As String
sMsg = gUI.ListviewToCSV(lvData)
    MessageBox.Show(sMsg)
End Sub

'A couple of overloads to allow for the hidden fields and a file name
Public Overloads Function ListviewToCSV(ByVal oLV As ListView) As String
    Dim sFile As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) & "\ListviewData.csv"
    Return ListviewToCSV(oLV, sFile)
End Function

Public Overloads Function ListviewToCSV(ByVal oLV As ListView, ByVal sFile As String) As String
    Return ListviewToCSV(oLV, sFile, False)
End Function

'The function that writes out the data to a CSV file
Public Overloads Function ListviewToCSV(ByVal oLV As ListView, ByVal sFile As String, ByVal bIncludeHidden As Boolean) As String
        Try
            Dim i As Integer
            Dim oItem As ListViewItem
            Dim sData As String = ""
            Dim sLine As String
            Dim Q As String = Chr(34)
            Dim QC As String = Chr(34) + ","

            'Create the header using the column headers
            sLine = Q + "ID" + QC
            For i = 0 To oLV.Columns.Count - 1
                'test for the hidden flag
                If bIncludeHidden Or oLV.Columns(i).Width > 0 Then
                    'remove any spaces from the header data
                    sLine += Q + Replace(oLV.Columns(i).Text, " ", "") + QC
                End If
            Next
            'Drop the trailing comma
            sData += DropChar(sLine, 1) + vbNewLine

            For Each oItem In oLV.Items
                sLine = IIf(IsNumeric(oItem.Tag), oItem.Tag + ",", Q + oItem.Tag + QC)
                For i = 0 To oItem.SubItems.Count - 1
                    If bIncludeHidden Or oLV.Columns(i).Width > 0 Then
                        'wrap the nonnumeric fields in quotes
                        sLine += IIf(IsNumeric(oItem.SubItems(i).Text), oItem.SubItems(i).Text + ",", Q + oItem.SubItems(i).Text + QC)
                    End If
                Next
                sData += DropChar(sLine, 1) + vbNewLine
            Next

            'Delete any existing file of the same name
            Dim oFI As New IO.FileInfo(sFile)
            If ofi.Exists Then
                oFI.Delete()
            End If
            Dim oFS As New IO.FileStream(sFile, IO.FileMode.CreateNew, IO.FileAccess.Write)
            Dim oSW As New IO.StreamWriter(oFS)
            oSW.Write(sData)
            oSW.Flush()
            oSW.Close()
            oFS.Close()
            Return "Listview exported to: " + sFile
        Catch Exc As Exception
            Return Exc.Message
        End Try
    End Function

'Oh and the DropChar thing
Public Shared Function DropChar(ByVal sText As String, Optional ByVal iCharToDrop As Integer = 1) As String
        Try
            Dim sTemp As String
            sTemp = Trim(LTrim(sText))
            sTemp = Str.Left(sTemp, sTemp.Length - iCharToDrop)
            Return sTemp
        Catch Exc As Exception
            Throw Exc
        End Try
    End Function

I hope this is a useful snippet.

Mark Firth

Popularity  (3306 Views)

Mark Firth posted at Tuesday, December 19, 2006 4:05 AM