Customizing the Menu

The menu used for displaying the fields of the field editors and the filter functions is a RadContexMenu. You can easily access it and customize it server-side as well as client-side.

Accessing the context menu

You access the context menu of the RadFilter server-side with the following code:

RadContextMenu menu = RadFilter1.FindControl("rfContextMenu") as RadContextMenu;

Dim menu As RadContextMenu = TryCast(RadFilter1.FindControl("rfContextMenu"), RadContextMenu)

To find it client-side, you can use the following code:

var filter = $find("<%=RadFilter1.ClientID %>");
var menu = filter.get_contextMenu();

Reducing the filter menu options

You can reduce the filter menu options to display only a subset of the available filter functions depending on the field. A suitable event for this is the OnClientShowing of the context menu of the RadFilter. In the code below the IsNull and NotIsNull filter options are hidden for System.Int32 data:

function pageLoad(sender, args) {
    var filter = $find("<%=RadFilter1.ClientID %>");
    var menu = filter.get_contextMenu();
    menu.add_showing(FilterMenuShowing);
}

function FilterMenuShowing(sender, args) {
    var filter = $find("<%=RadFilter1.ClientID %>");
    var currentExpandedItem = sender.get_attributes()._data.ItemHierarchyIndex;
    var fieldName = filter._expressionItems[currentExpandedItem];
    var allFields = filter._dataFields;
    var dataType = null;
    for (var i = 0, j = allFields.length; i < j; i++) {
        if (allFields[i].FieldName == fieldName) {
            dataType = allFields[i].DataType;
            break;
        }
    }
    if (dataType == "System.Int32") {
        sender.findItemByValue("IsNull").set_visible(false);
        sender.findItemByValue("NotIsNull").set_visible(false);
    }
}

Note that the filter has a default function that is shown in the filter editor row regardless of the context menu. If you want to hide that as well, you need to choose a different option when the current editor is created in the server FieldEditorCreated event.

For example, a ShipVia column will only have the GreaterThan option with the snippets below.

If there is going to only be one option, also make sure to .click() it instead of hiding it when the menu is about to show. This will invoke the actual filter operation that the user cannot otherwise call without the menu options.

<telerik:RadFilter RenderMode="Lightweight" runat="server" ID="RadFilter1" FilterContainerID="RadGrid1" ShowApplyButton="false" OnFieldEditorCreated="RadFilter1_FieldEditorCreated"></telerik:RadFilter>

<telerik:RadGrid RenderMode="Lightweight" runat="server" ID="RadGrid1" AutoGenerateColumns="false" DataSourceID="SqlDataSource1" AllowPaging="true" AllowSorting="true" AllowFilteringByColumn="true" OnItemCommand="RadGrid1_ItemCommand">
    <MasterTableView IsFilterItemExpanded="false" CommandItemDisplay="Top">
        <CommandItemTemplate>
            <telerik:RadToolBar RenderMode="Lightweight" runat="server" ID="RadToolBar1" AutoPostBack="true">
                <Items>
                    <telerik:RadToolBarButton Text="Apply filter" CommandName="FilterRadGrid" ImagePosition="Right"></telerik:RadToolBarButton>
                </Items>
            </telerik:RadToolBar>
        </CommandItemTemplate>
        <Columns>
            <telerik:GridNumericColumn DataField="OrderID" HeaderText="OrderID" DataType="System.Int32"></telerik:GridNumericColumn>
            <telerik:GridDateTimeColumn DataField="OrderDate" HeaderText="OrderDate" DataFormatString="{0:MM/dd/yyyy}"></telerik:GridDateTimeColumn>
            <telerik:GridNumericColumn DataField="ShipVia" HeaderText="ShipVia" DataType="System.Int32"></telerik:GridNumericColumn>
            <telerik:GridBoundColumn DataField="ShipName" HeaderText="ShipName"></telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="ShipAddress" HeaderText="ShipAddress"></telerik:GridBoundColumn>
            <telerik:GridNumericColumn DataField="Freight" HeaderText="Freight" DataType="System.Decimal"></telerik:GridNumericColumn>
        </Columns>
    </MasterTableView>
</telerik:RadGrid>

<asp:SqlDataSource runat="server" ID="SqlDataSource1" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>" SelectCommand="Select OrderID, OrderDate, ShipVia, ShipName, ShipAddress, Freight FROM Orders"></asp:SqlDataSource>

<script>
    function FilterMenuShowing(sender, args) {
        var filter = $find("<%=RadFilter1.ClientID %>");
        var currentExpandedItem = sender.get_attributes()._data.ItemHierarchyIndex;
        var fieldName = filter._expressionItems[currentExpandedItem];
        if (fieldName == "ShipVia") { //we choose to modify the ShipVia field
            sender.findItemByValue("EqualTo").set_visible(false);
            //sender.findItemByValue("Contains").set_visible(false);
            sender.findItemByValue("IsNull").set_visible(false);
            sender.findItemByValue("DoesNotContain").set_visible(false);
            sender.findItemByValue("StartsWith").set_visible(false);
            sender.findItemByValue("EndsWith").set_visible(false);
            sender.findItemByValue("NotEqualTo").set_visible(false);
            sender.findItemByValue("GreaterThanOrEqualTo").set_visible(false);
            sender.findItemByValue("LessThanOrEqualTo").set_visible(false);
            sender.findItemByValue("Between").set_visible(false);
            sender.findItemByValue("NotBetween").set_visible(false);
            sender.findItemByValue("IsEmpty").set_visible(false);
            sender.findItemByValue("NotIsEmpty").set_visible(false);
            sender.findItemByValue("NotIsNull").set_visible(false);
            sender.findItemByValue("GreaterThan").set_visible(false);

            //let's say that we want to use only this filter
            sender.findItemByValue("GreaterThan").click();

            sender.findItemByValue("LessThan").set_visible(false);
            sender.findItemByValue("NotOr").set_visible(false);
            sender.findItemByValue("NotAnd").set_visible(false);
            sender.findItemByValue("Or").set_visible(false);
        }
    }

    function pageLoad(sender, args) {
        var filter = $find("<%=RadFilter1.ClientID %>");
        var menu = filter.get_contextMenu();
        menu.add_showing(FilterMenuShowing);
    }
</script>

protected void RadGrid1_ItemCommand(object source, GridCommandEventArgs e)
{
    if (e.CommandName == "FilterRadGrid")
    {
        RadFilter1.FireApplyCommand();
    }
}


protected void RadFilter1_FieldEditorCreated(object sender, RadFilterFieldEditorCreatedEventArgs e)
{
    //this has to match the client-side code
    if(e.Editor.FieldName == "ShipVia")
    {
        e.Editor.DefaultFilterFunction = RadFilterFunction.GreaterThan;
    }
}

Protected Sub RadGrid1_ItemCommand(ByVal source As Object, ByVal e As GridCommandEventArgs)
    If e.CommandName = "FilterRadGrid" Then
        RadFilter1.FireApplyCommand()
    End If
End Sub

Protected Sub RadFilter1_FieldEditorCreated(ByVal sender As Object, ByVal e As RadFilterFieldEditorCreatedEventArgs)
    'this has to match the client-side code'
    If e.Editor.FieldName = "ShipVia" Then
        e.Editor.DefaultFilterFunction = RadFilterFunction.GreaterThan
    End If
End Sub