`actionHandler`

Use actionHandler to call Gosu on the server side, get a result back, and then render the page again. For example, if you have a button in your panel that navigates to another PCF page, then you would need to use an actionHandler. The handler could call SomePage.go(), and PolicyCenter would go through its usual cycle to rebuild and render the widget tree. Note that the TemplatePanel may be removed from the tree in the process. If you navigate to another PCF page, then the panel will definitely be discarded. Even if you stay on the same PCF page, the panel may be rendered again, depending on how much changed.

The actionHandler must conform to the following interface:

public interface TemplatePanelActionHandler {
  void action(gw.api.json.JsonObject json);
}

Because this interface has only one method, you can implement it with a Gosu block. Within the template, call the action handler from JavaScript using the gw.api.submitTemplateAction API. Pass gw.api.submitTemplateAction the following:

The ID of the template panel. The ID is provided by substituting in the value __helper.TemplatePanelId. The __helper variable is provided as part of the context to the template panel.
A JSON object to send to the server.

The following is an example of calling gw.api.submitTemplateAction within a template:

gw.api.submitTemplateAction("<%=__helper.TemplatePanelId%>", {name: typeName});

When this JavaScript is executed on the client side, it calls the server with the specified template panel ID and JSON. The server looks up the Gosu actionHandler for the template panel and executes it, passing the JSON as its argument. PolicyCenter then goes through its usual request life cycle, updating and rendering all PCF widgets again.