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How to Create a custom Data Collector

How to Create a custom Data Collector

The Symfony Profiler obtains its profiling and debug information using some special classes called data collectors. Symfony comes bundled with a few of them, but you can also create your own.

Creating a custom Data Collector

A data collector is a PHP class that implements the Symfony\Component\HttpKernel\DataCollector\DataCollectorInterface. For convenience, your data collectors can also extend from the Symfony\Bundle\FrameworkBundle\DataCollector\AbstractDataCollector class, which implements the interface and provides some utilities and the $this->data property to store the collected information.

New in version 5.2: The AbstractDataCollector class was introduced in Symfony 5.2.

The following example shows a custom collector that stores information about the request:

// src/DataCollector/RequestCollector.php
namespace App\DataCollector;

use Symfony\Bundle\FrameworkBundle\DataCollector\AbstractDataCollector;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\DataCollector\DataCollector;

class RequestCollector extends AbstractDataCollector
{
    public function collect(Request $request, Response $response, \Throwable $exception = null)
    {
        $this->data = [
            'method' => $request->getMethod(),
            'acceptable_content_types' => $request->getAcceptableContentTypes(),
        ];
    }
}

These are the method that you can define in the data collector class:

collect() method:

Stores the collected data in local properties ($this->data if you extend from AbstractDataCollector). If you need some services to collect the data, inject those services in the data collector constructor.

Caution

The collect() method is only called once. It is not used to “gather” data but is there to “pick up” the data that has been stored by your service.

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.

reset() method:
It’s called between requests to reset the state of the profiler. By default it only empties the $this->data contents, but you can override this method to do additional cleaning.
getName() method:
Returns the collector identifier, which must be unique in the application. By default it returns the FQCN of the data collector class, but you can override this method to return a custom name (e.g. app.request_collector). This value is used later to access the collector information (see How to Use the Profiler in a Functional Test) so you may prefer using short strings instead of FQCN strings.

The collect() method is called during the kernel.response event. If you need to collect data that is only available later, implement Symfony\Component\HttpKernel\DataCollector\LateDataCollectorInterface and define the lateCollect() method, which is invoked right before the profiler data serialization (during kernel.terminate event).

Note

If you’re using the default services.yaml configuration with autoconfigure, then Symfony will start using your data collector after the next page refresh. Otherwise, enable the data collector by hand.

Adding Web Profiler Templates

The information collected by your data collector can be displayed both in the web debug toolbar and in the web profiler. To do so, you need to create a Twig template that includes some specific blocks.

First, add the getTemplate() method in your data collector class to return the path of the Twig template to use. Then, add some getters to give the template access to the collected information:::

// src/DataCollector/RequestCollector.php
namespace App\DataCollector;

use Symfony\Bundle\FrameworkBundle\DataCollector\AbstractDataCollector;

class RequestCollector extends AbstractDataCollector
{
    // ...

    public static function getTemplate(): ?string
    {
        return 'data_collector/template.html.twig';
    }

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

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

In the simplest case, you want to display the information in the toolbar without providing a profiler panel. This requires to define the toolbar block and set the value of two variables called icon and text:

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{# templates/data_collector/template.html.twig #}
{% extends '@WebProfiler/Profiler/layout.html.twig' %}

{% block toolbar %}
    {% set icon %}
        {# this is the content displayed as a panel in the toolbar #}
        <svg xmlns="http://www.w3.org/2000/svg"> ... </svg>
        <span class="sf-toolbar-value">Request</span>
    {% endset %}

    {% set text %}
        {# this is the content displayed when hovering the mouse over
           the toolbar panel #}
        <div class="sf-toolbar-info-piece">
            <b>Method</b>
            <span>{{ collector.method }}</span>
        </div>

        <div class="sf-toolbar-info-piece">
            <b>Accepted content type</b>
            <span>{{ collector.acceptableContentTypes|join(', ') }}</span>
        </div>
    {% endset %}

    {# the 'link' value set to 'false' means that this panel doesn't
       show a section in the web profiler #}
    {{ include('@WebProfiler/Profiler/toolbar_item.html.twig', { link: false }) }}
{% endblock %}

Tip

Built-in collector templates define all their images as embedded SVG files. This makes them work everywhere without having to mess with web assets links:

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{% set icon %}
    {{ include('data_collector/icon.svg') }}
    {# ... #}
{% endset %}

If the toolbar panel includes extended web profiler information, the Twig template must also define additional blocks:

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{# templates/data_collector/template.html.twig #}
{% extends '@WebProfiler/Profiler/layout.html.twig' %}

{% block toolbar %}
    {% set icon %}
        {# ... #}
    {% endset %}

    {% set text %}
        <div class="sf-toolbar-info-piece">
            {# ... #}
        </div>
    {% endset %}

    {{ include('@WebProfiler/Profiler/toolbar_item.html.twig', { 'link': true }) }}
{% endblock %}

{% block head %}
    {# Optional. Here you can link to or define your own CSS and JS contents. #}
    {# Use {{ parent() }} to extend the default styles instead of overriding them. #}
{% endblock %}

{% block menu %}
    {# This left-hand menu appears when using the full-screen profiler. #}
    <span class="label">
        <span class="icon"><img src="..." alt=""/></span>
        <strong>Request</strong>
    </span>
{% endblock %}

{% block panel %}
    {# Optional, for showing the most details. #}
    <h2>Acceptable Content Types</h2>
    <table>
        <tr>
            <th>Content Type</th>
        </tr>

        {% for type in collector.acceptableContentTypes %}
        <tr>
            <td>{{ type }}</td>
        </tr>
        {% endfor %}
    </table>
{% endblock %}

The menu and panel blocks are the only required blocks to define the contents displayed in the web profiler panel associated with this data collector. All blocks have access to the collector object.

Note

The position of each panel in the toolbar is determined by the collector priority, which can only be defined when configuring the data collector by hand.

Note

If you’re using the default services.yaml configuration with autoconfigure, then Symfony will start displaying your collector data in the toolbar after the next page refresh. Otherwise, enable the data collector by hand.

Enabling Custom Data Collectors

If you don’t use Symfony’s default configuration with autowire and autoconfigure you’ll need to configure the data collector explicitly:

  • YAML
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    # config/services.yaml
    services:
        App\DataCollector\RequestCollector:
            tags:
                -
                    name: data_collector
                    # must match the value returned by the getName() method
                    id: 'App\DataCollector\RequestCollector'
                    # optional template (it has more priority than the value returned by getTemplate())
                    template: 'data_collector/template.html.twig'
                    # optional priority (positive or negative integer; default = 0)
                    # priority: 300
    
  • XML
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    <!-- config/services.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <container xmlns="http://symfony.com/schema/dic/services"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            https://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <services>
            <service id="App\DataCollector\RequestCollector">
                <!-- the 'template' attribute has more priority than the value returned by getTemplate() -->
                <tag name="data_collector"
                    id="App\DataCollector\RequestCollector"
                    template="data_collector/template.html.twig"
                />
                <!-- optional 'priority' attribute (positive or negative integer; default = 0) -->
                <!-- priority="300" -->
            </service>
        </services>
    </container>
    
  • PHP
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    // config/services.php
    namespace Symfony\Component\DependencyInjection\Loader\Configurator;
    
    use App\DataCollector\RequestCollector;
    
    return function(ContainerConfigurator $configurator) {
        $services = $configurator->services();
    
        $services->set(RequestCollector::class)
            ->tag('data_collector', [
                'id' => RequestCollector::class,
                // optional template (it has more priority than the value returned by getTemplate())
                'template' => 'data_collector/template.html.twig',
                // optional priority (positive or negative integer; default = 0)
                // 'priority' => 300,
            ]);
    };
    

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