php-debugbar/docs/data_collectors.md

Collecting Data

Using collectors

Collectors can be added to your debug bar using addCollector().

$debugbar = new DebugBar();
$debugbar->addCollector(new DataCollector\RequestDataCollector());

Each collector as a unique name as defined by its getName() method. You can access collectors using getCollector($name).

$debugbar->addCollector(new DataCollector\MessagesCollector());
$debugbar->getCollector('messages')->addMessage("foobar");
// or:
$debugbar['messages']->addMessage("foobar");

Data will be collected from them when the debug bar is rendered. You can however collect the data earlier using collect().

$debugbar->collect();

Creating collectors

Collectors must implement the DebugBar\DataCollector\DataCollectorInterface. They may subclass DebugBar\DataCollector\DataCollector which provides utility methods.

Collectors must provide a getName() function returning their unique name and a collect() function returning some json-encodable data. The latter will be called at the same time the DebugBar::collect() method is called.

class MyDataCollector extends DebugBar\DataCollector\DataCollector
{
    public function collect()
    {
        return array("uniqid" => uniqid());
    }

    public function getName()
    {
        return 'mycollector';
    }
}

$debugbar->addCollector(new MyDataCollector());

This however won't show anything in the debug bar as no information are provided on how to display these data. You could do that manually as you'll see in later chapter or implement the DebugBar\DataSource\Renderable interface.

To implement it, you must define a getWidgets() function which returns an array of key/value pairs where key are control names and values control options as defined in JavascriptRenderer::addControl($name, $options) (see Rendering chapter).

class MyDataCollector extends DebugBar\DataCollector\DataCollector implements DebugBar\DataCollector\Renderable
{
    // ...

    public function getWidgets()
    {
        return array(
            "mycollector" => array(
                "icon" => "cogs",
                "tooltip" => "uniqid()",
                "map" => "uniqid",
                "default" => "''"
            )
        );
    }
}

This will have the result of adding a new indicator to the debug bar.