Passing Values to a Controller Action through Callbacks

• Oct 29, 2020
• 2 minutes to read

When a DevExpress MVC extension works in callback mode and requests the server via its own callback, you can use this callback to pass custom values collected on the client for further server processing. On the server side, you can process these values within a Controller action that is specified by the extension’s CallbackRouteValues property. Depending upon the passed values, you can conditionally form the response to be sent back to the client.

By design, a callback (initiated by a DevExpress MVC extension) automatically passes values to the server. These are specific extension-related values, and the values of all internal form elements (e.g., input, textarea, select) rendered inside our extensions. To pass custom values from the client via a callback, you should handle an extension-specific BeginCallback client event. This event’s argument provides you with the MVCxClientBeginCallbackEventArgs.customArgs property. This property represents a hash table object that can contain named values. Any named value assigned to the customArgs property is then passed to the server as a request parameter. On the server side, it can be accessed as a parameter of the specified Action. So, the necessary server-side actions can be performed in the handling Action based upon the value(s) passed from the client.

View:

• JS

function OnBeginCallback(s, e) {
        e.customArgs["Value1"] = 1;
        e.customArgs["Value2"] = 2;
    }

Controller:

• C#

public ActionResult MyView(int value1, int value2) {
        ...
    }

The following table lists DevExpress MVC extensions that expose the BeginCallback client event.

For an example of how to pass and process client values, refer to the following online demo: Callback Panel - Example.

See Also

Using Callbacks