Using Callbacks

• Aug 01, 2019
• 6 minutes to read

Some DevExpress MVC extensions can work in callback mode by requesting the server via their own callbacks. Using callbacks is an efficient way to load/update extension content on demand (to minimize the initial data transfer) or to perform some lengthy functional operations (such as file uploads).

The following requirements should be met for an extension that is used in callback mode.

• An extension should be defined in a separate Partial View (.cshtml or .vbhtml).

  Note

  It is required that a Partial View contains only the extension definition code, without any additional markup.

• A Controller should contain an additional Action method to handle extension callbacks and route them directly to a Partial View containing the extension. This allows the extension render to be conditionally updated in response to the end-user action performed.
• Callback routing logic should be defined using a CallbackRouteValues property of an extension’s settings object. This property allows the names of the callback handling Controller and Action to be specified.

Note that these requirements are not required for all extensions that support the use of callbacks. For instance, the UploadControl extension might not be declared within a Partial View - it is enough for it to properly implement a callback handler Action method and reference this method in the CallbackRouteValues property’s value.

Extensions That Can Use Callbacks

The table below lists DevExpress MVC extensions that support the use of callbacks.

Extension	Callback Mode Availability	Requirements for Callback Mode Realization
Calendar	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (CalendarSettings.CallbackRouteValues)
CallbackPanel	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (CallbackPanelSettings.CallbackRouteValues)
Charting	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (ChartControlSettings.CallbackRouteValues)
ComboBox	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (AutoCompleteBoxBaseSettings.CallbackRouteValues)
DataView	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (DataViewSettings.CallbackRouteValues)
DateEdit	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (DateEditSettings.CallbackRouteValues)
DockManager	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (DockManagerSettings.CallbackRouteValues)
DockPanel	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (PopupControlSettingsBase.CallbackRouteValues)
DocumentViewer	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (ReportViewerSettings.CallbackRouteValues)
GridView	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (GridSettingsBase.CallbackRouteValues)
HtmlEditor	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (HtmlEditorSettings.CallbackRouteValues)
ListBox	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (ListBoxSettings.CallbackRouteValues)
Menu	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (MenuSettings.CallbackRouteValues)
NavBar	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (NavBarSettings.CallbackRouteValues)
PageControl	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (PageControlSettings.CallbackRouteValues)
PivotGrid	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (PivotGridSettings.CallbackRouteValues)
PopupControl	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (PopupControlSettingsBase.CallbackRouteValues)
PopupMenu	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (PopupMenuSettings.CallbackRouteValues)
RichEdit	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (RichEditSettings.CallbackRouteValues)
Scheduler	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (SchedulerSettings.CallbackRouteValues)
Spreadsheet	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (SpreadsheetSettings.CallbackRouteValues)
TreeList	Always	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (TreeListSettings.CallbackRouteValues)
TreeView	Optional	Define extension in a separate Partial View. Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (TreeViewSettings.CallbackRouteValues)
UploadControl	Optional	Implement an Action method within the Controller to handle extension callbacks. Specify the Controller and Action names via the CallbackRouteValues property. (UploadControlSettings.CallbackRouteValues)

Example

This example demonstrates how the use of callbacks can be implemented for the TreeView extension.

View Code - “Callbacks” (ASPX)

C#

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %>

<asp:Content ID="indexContent" ContentPlaceHolderID="ContentHolder" runat="server">
    <% 
        Html.RenderPartial("CallbacksPartial");
    %>
</asp:Content>

View Code - “Callbacks” (Razor)

C#

@Html.Partial("CallbacksPartial")

PartialView code - “CallbacksPartial” (ASPX):

C#

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %>

<% 
    Html.DevExpress().TreeView(
        settings =>
        {
            settings.Name = "tvCallbacks";
            settings.CallbackRouteValues = new { Controller = "TreeView", Action = "CallbacksPartial" };
        })
        .BindToSiteMap("~/App_Data/Feature.sitemap", false)
        .Render();
%>

PartialView code - “CallbacksPartial” (Razor):

C#

@Html.DevExpress().TreeView(
    settings =>
    {
        settings.Name = "tvCallbacks";
        settings.CallbackRouteValues = new { Controller = "TreeView", Action = "CallbacksPartial" };
    }).BindToSiteMap("~/App_Data/Feature.sitemap", false).GetHtml()

Controller (“TreeViewController”):

C#

    public class TreeViewController: Controller {

        public ActionResult Callbacks() {
            return DemoView("Callbacks");
        }

        public ActionResult CallbacksPartial() {
            return PartialView("CallbacksPartial");
        }

    }