php-debugbar/docs/ajax_and_stack.md

AJAX and Stacked data

AJAX

As mentioned in the previous chapter, if you are performing AJAX requests which return HTML content, you can use JavascriptRenderer::render(false).

In the case you are sending back non-HTML data (eg: JSON), the DebugBar can send data to the client using HTTP headers using the sendDataInHeaders() method (no need to use the JavascriptRenderer):

$debugbar = new DebugBar();
// ...
$debugbar->sendDataInHeaders();

On the client side, an instance of PhpDebugBar.AjaxHandler will parse the headers and add the dataset to the debugbar.

The AjaxHandler automatically binds to jQuery's ajaxComplete event so if you are using jQuery, you have nothing to configure.

If you're not using jQuery, you can call AjaxHandler.handle(xhr). If you are using the JavascriptRenderer initialization, the instance of AjaxHandler is stored in the ajaxHandler property of the DebugBar object.

debugbar.ajaxHandler.handle(xhr);

If you are sending a lot of data through headers, it may cause problems with your browser. Instead you can use a storage handler (see Storage chapter) and the open handler (see Open Handler chapter) to load the data after an ajax request. Use true as the first argument of sendDataInHeaders().

$debugbar = new DebugBar();

// define a storage
$debugbar->setStorage(new DebugBar\Storage\FileStorage('/path/to/storage'));

// define the open handler url
$renderer = $debugbar->getJavascriptRenderer();
$renderer->setOpenHandlerUrl('open.php');

// ...

$debugbar->sendDataInHeaders(true);

By default, the debug bar will immediately show new AJAX requests. If your page makes a lot of requests in the background (e.g. tracking), this can be disruptive. You can disable this behavior by calling setAjaxHandlerAutoShow(false) on the JavascriptRenderer, like this:

$renderer = $debugbar->getJavascriptRenderer();
$renderer->setAjaxHandlerAutoShow(false);

Stacked data

Some times you need to collect data about a request but the page won't actually be displayed. The best example of that is during a redirect. You can use the debug bar storage mechanism to store the data and re-open it later but it can be cumbersome while testing a redirect page.

The solution is to use stacked data. The debug bar can temporarily store the collected data in the session until the next time it will be displayed. Simply call DebugBar::stackData() instead of rendering the debug bar.

PHP's session must be started before using this feature.

Note: The stacked data feature will use the storage mechanism if it's enabled instead of storing the data in the session.

$debugbar = new DebugBar();
// ...
$debugbar->stackData();

Stacked data are rendered each time the debug bar is rendered using the JavascriptRenderer.