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How to create a custom Data Collector

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How to create a custom Data Collector

The Symfony2 Profiler delegates data collecting to data collectors. Symfony2 comes bundled with a few of them, but you can easily create your own.

Creating a Custom Data Collector

Creating a custom data collector is as simple as implementing the DataCollectorInterface:

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interface DataCollectorInterface
{
    /**
     * Collects data for the given Request and Response.
     *
     * @param Request    $request   A Request instance
     * @param Response   $response  A Response instance
     * @param \Exception $exception An Exception instance
     */
    function collect(Request $request, Response $response, \Exception $exception = null);

    /**
     * Returns the name of the collector.
     *
     * @return string The collector name
     */
    function getName();
}

The getName() method must return a unique name. This is used to access the information later on (see How to use the Profiler in a Functional Test for instance).

The collect() method is responsible for storing the data it wants to give access to in local properties.

Caution

As the profiler serializes data collector instances, you should not store objects that cannot be serialized (like PDO objects), or you need to provide your own serialize() method.

Most of the time, it is convenient to extend DataCollector and populate the $this->data property (it takes care of serializing the $this->data property):

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class MemoryDataCollector extends DataCollector
{
    public function collect(Request $request, Response $response, \Exception $exception = null)
    {
        $this->data = array(
            'memory' => memory_get_peak_usage(true),
        );
    }

    public function getMemory()
    {
        return $this->data['memory'];
    }

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

Enabling Custom Data Collectors

To enable a data collector, add it as a regular service in one of your configuration, and tag it with data_collector:

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    services:
        data_collector.your_collector_name:
            class: Fully\Qualified\Collector\Class\Name
            tags:
                - { name: data_collector }
    
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    <service id="data_collector.your_collector_name" class="Fully\Qualified\Collector\Class\Name">
        <tag name="data_collector" />
    </service>
    
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    $container
        ->register('data_collector.your_collector_name', 'Fully\Qualified\Collector\Class\Name')
        ->addTag('data_collector')
    ;
    

Adding Web Profiler Templates

When you want to display the data collected by your Data Collector in the web debug toolbar or the web profiler, create a Twig template following this skeleton:

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{% extends 'WebProfilerBundle:Profiler:layout.html.twig' %}

{% block toolbar %}
    {# the web debug toolbar content #}
{% endblock %}

{% block head %}
    {# if the web profiler panel needs some specific JS or CSS files #}
{% endblock %}

{% block menu %}
    {# the menu content #}
{% endblock %}

{% block panel %}
    {# the panel content #}
{% endblock %}

Each block is optional. The toolbar block is used for the web debug toolbar and menu and panel are used to add a panel to the web profiler.

All blocks have access to the collector object.

Tip

Built-in templates use a base64 encoded image for the toolbar (<img src="data:image/png;base64,..."). You can easily calculate the base64 value for an image with this little script: echo base64_encode(file_get_contents($_SERVER['argv'][1]));.

To enable the template, add a template attribute to the data_collector tag in your configuration. For example, assuming your template is in some AcmeDebugBundle:

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    services:
        data_collector.your_collector_name:
            class: Acme\DebugBundle\Collector\Class\Name
            tags:
                - { name: data_collector, template: "AcmeDebugBundle:Collector:templatename", id: "your_collector_name" }
    
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    <service id="data_collector.your_collector_name" class="Acme\DebugBundle\Collector\Class\Name">
        <tag name="data_collector" template="AcmeDebugBundle:Collector:templatename" id="your_collector_name" />
    </service>
    
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    $container
        ->register('data_collector.your_collector_name', 'Acme\DebugBundle\Collector\Class\Name')
        ->addTag('data_collector', array(
            'template' => 'AcmeDebugBundle:Collector:templatename',
            'id'       => 'your_collector_name',
        ))
    ;
    

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.