Using a CommandItemTemplate to filter an entire Radgrid with 1 searchbar

[William]

I have the radgrid and commandItemTemplate as follows:

<telerik:RadGrid RenderMode="Lightweight" runat="server" ID="calendarTableView" OnItemCommand="ItemCommand" >
    <MasterTableView AutoGenerateColumns="false" TableLayout="Fixed" CommandItemDisplay="Top">
        <CommandItemTemplate>
            <asp:TextBox ID="txtFilter" runat="server"></asp:TextBox>
            <asp:Button ID="btnFilter" runat="server" Text="Apply Filter" CommandName="FilterAll" />
            <asp:Button ID="btnClear" runat="server" Text="Clear Filter" CommandName="ClearFilter" />
        </CommandItemTemplate>
    </MasterTableView>
</telerik:RadGrid>

and in the vb file I have

Protected Sub ItemCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs)
    Dim filterExpression As String = String.Empty
    If e.CommandName = "FilterAll" Then
        Dim cmdItem As GridCommandItem = TryCast(e.Item, GridCommandItem)
        Dim txtFilter = TryCast(cmdItem.FindControl("txtFilter"), TextBox)
        For Each col As GridColumn In calendarTableView.MasterTableView.Columns
            For Each dataItem As GridDataItem In calendarTableView.Items
                If dataItem(col.UniqueName).Text.Contains(txtFilter.Text) Then
                    filterExpression = "([" + col.UniqueName + "] = '%" + txtFilter.Text + "%')"
                    calendarTableView.MasterTableView.FilterExpression = filterExpression
                End If
            Next
        Next
        calendarTableView.MasterTableView.Rebind()
    ElseIf e.CommandName = "ClearFilter" Then
        Dim cmdItem As GridCommandItem = TryCast(e.Item, GridCommandItem)
        Dim txtFilter As TextBox = TryCast(cmdItem.FindControl("txtFilter"), TextBox)
        txtFilter.Text = String.Empty
        calendarTableView.MasterTableView.FilterExpression = String.Empty
    End If
End Sub

 

but I am running into 2 problems.  1, it's not getting the text from the txtFilter textbox correctly and 2, the line " calendarTableView.MasterTableView.Rebind() " comes up with an exception saying it expected an expression.

[Marin Bratanov]

Hi,

If the default grid filtering experience (see here and here) does not match your needs, you can also consider another built-in integration - with RadFilter: https://demos.telerik.com/aspnet-ajax/filter/examples/integration/defaultcs.aspx?product=filter.

If you would still like to proceed with custom filtering, I advise that you consider filtering the data source itself rather than hacking through the grid. You can easily do that in the NeedDataSource event by processing the data according to the desired logic before passing it to the grid.

Doing this manually is actually going to be rather hard and the provided code will have a lot of limitations. Nevertheless, I modified it so you can get started, and I also left comments with the issues and resources you can use to get things done:

<telerik:RadGrid RenderMode="Lightweight" runat="server" ID="calendarTableView" OnItemCommand="ItemCommand" OnNeedDataSource="calendarTableView_NeedDataSource">
    <MasterTableView AutoGenerateColumns="false" TableLayout="Fixed" CommandItemDisplay="Top">
        <CommandItemTemplate>
            <asp:TextBox ID="txtFilter" runat="server"></asp:TextBox>
            <asp:Button ID="btnFilter" runat="server" Text="Apply Filter" CommandName="FilterAll" />
            <asp:Button ID="btnClear" runat="server" Text="Clear Filter" CommandName="ClearFilter" />
        </CommandItemTemplate>
        <Columns>
            <telerik:GridBoundColumn DataField="someField" HeaderText="some field"></telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="otherField" HeaderText="other field"></telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="thirdField" HeaderText="third field"></telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="fourthField" HeaderText="fourth field"></telerik:GridBoundColumn>
        </Columns>
    </MasterTableView>
</telerik:RadGrid>

Protected Sub ItemCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs)
    Dim filterExpression As String = String.Empty
    If e.CommandName = "FilterAll" Then
        'see https://docs.telerik.com/devtools/aspnet-ajax/controls/grid/how-to/Common/using-the--getitems-getcolumn-and-getcolumnsafe-methods
        Dim cmdItem As GridCommandItem = calendarTableView.MasterTableView.GetItems(GridItemType.CommandItem)(0)
        'TryCast(e.Item, GridCommandItem)
        Dim txtFilter = TryCast(cmdItem.FindControl("txtFilter"), TextBox)
        'these loops are unnecessary, it is similar to the operation that needs to be done on the data source for filtering anyway
        'also,they will only go through the data on the current page as the grid creates items only for the current page (for performance reasons)
        'which is why such custom filtering is best implemented over the data source rather than hacking through the grid
        'also, with this code the filter expression will be applied only for the last column where a text occurence exists
        For Each col As GridColumn In calendarTableView.MasterTableView.Columns
            For Each dataItem As GridDataItem In calendarTableView.Items
                If dataItem(col.UniqueName).Text.Contains(txtFilter.Text) Then
                    'sample to aim for
                    '@"it[""CustomerID""].ToString().Contains(""ALFKI"")"
                    'see more at https://docs.telerik.com/devtools/aspnet-ajax/controls/grid/how-to/Filtering/operate-with-the-filterexpression-manually
                    filterExpression = "it[""" + col.UniqueName + """].ToString().Contains(""" + txtFilter.Text + """)"
                    calendarTableView.MasterTableView.FilterExpression = filterExpression
                End If
            Next
        Next
        If (Not String.IsNullOrEmpty(filterExpression)) Then
            'if you won't be doing operations on the grid, you do not really need to rebind it
            calendarTableView.MasterTableView.Rebind()
        End If
    ElseIf e.CommandName = "ClearFilter" Then
        Dim cmdItem As GridCommandItem = calendarTableView.MasterTableView.GetItems(GridItemType.CommandItem)(0)
        'Dim cmdItem As GridCommandItem = TryCast(e.Item, GridCommandItem)
        Dim txtFilter As TextBox = TryCast(cmdItem.FindControl("txtFilter"), TextBox)
        txtFilter.Text = String.Empty

        'see https://www.telerik.com/support/kb/aspnet-ajax/grid/details/how-to-clear-radgrid-filters

        For Each col As GridColumn In calendarTableView.MasterTableView.Columns
            col.ListOfFilterValues = Nothing
            col.CurrentFilterFunction = GridKnownFunction.NoFilter
            col.CurrentFilterValue = String.Empty
        Next

        calendarTableView.MasterTableView.FilterExpression = String.Empty
    End If
End Sub


Protected Function GetTestData() As DataTable
    Dim tbl As New DataTable()
    tbl.Columns.Add(New DataColumn("someField", GetType(String)))
    tbl.Columns.Add(New DataColumn("otherField", GetType(String)))
    tbl.Columns.Add(New DataColumn("thirdField", GetType(Integer)))
    tbl.Columns.Add(New DataColumn("fourthField", GetType(String)))
    tbl.Rows.Add(New Object() {"first", "firstRecord2", 1, "A"})
    tbl.Rows.Add(New Object() {"first", "secondRecord2", 2, "B"})
    tbl.Rows.Add(New Object() {"third", "thirdRecord2", 3, "C"})
    Return tbl
End Function

Protected Sub calendarTableView_NeedDataSource(sender As Object, e As GridNeedDataSourceEventArgs)
    DirectCast(sender, RadGrid).DataSource = GetTestData()
End Sub

Regards,
Marin Bratanov
Progress Telerik