RssAtomBundle - Read and Build Atom/RSS feeds

RssAtomBundle is a Bundle for Symfony made to easily access and deliver JSON / RSS / Atom feeds. It is built on top of feed-io and features:

• Detection of the feed format (JSON / RSS / Atom)
• enclosures support
• A generic StreamController built to write all your feeds. This controller is able to send a 304 HTTP Code if the feed didn't change since the last visit
• HTTP Headers support when reading feeds in order to save network traffic
• Content filtering to fetch only the newest items
• multiple feeds writing
• Ability to use doctrine as a data source
• PSR compliant logging
• DateTime detection and conversion
• Guzzle Client integration

Keep informed about new releases and incoming features : http://debril.org/category/rss-atom-bundle

You can try rss-atom-bundle through its Demo.

Installation

Dependencies

As a Symfony Bundle, RssAtomBundle must be installed using Composer. If you do not know Composer, please refer to its website: http://getcomposer.org/

Your application uses Symfony 3.3 or later

Activate Symfony's contrib recipes and use Composer to require the bundle :

composer config extra.symfony.allow-contrib true
composer require debril/rss-atom-bundle

That's it. To check the installation, you can start your application and hit http://localhost:8000/rss in your browser. You should see a mock RSS stream.

If your application uses Symfony < 3.3

Install the bundle using Composer :

composer require debril/rss-atom-bundle

Add the bundle's routing configuration in app/config/routing.yml :

rssatom:
    resource: "@DebrilRssAtomBundle/Resources/config/routing.yml"

Edit your app/AppKernel.php to register the bundle in the registerBundles() method as above:

class AppKernel extends Kernel
{

    public function registerBundles()
    {
        $bundles = array(
            new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
            // ...
            // register the bundle here
            new Debril\RssAtomBundle\DebrilRssAtomBundle(),

Usage

rss-atom-bundle is designed to read feeds across the internet and to publish your own using feed-io feed-io provides two interfaces, each one being dedicated to feed's consuming and publishing :

• FeedInterface to handle the feed
• ItemInterface to handle feed's items

Getting a FeedIo instance

You can fetch a FeedIo\FeedIo instance through dependency injection or the service container.

Dependency injection (highly recommended)

namespace App\Feed;

class Consumer
{

    /**
     * @type \FeedIo\FeedIo
     */
    private $feedIo;

    public function __construct(FeedIo $feedIo)
    {
        $this->feedIo = $feedIo;
    }
}

Service Container

Wherever you have access to the service container :

<?php
    // get feedio
    $feedIo = $this->container->get('feedio');

Feed Reading

To read a feed you need to use the feedio service which provides two methods for that : read() and readSince(). This service is based upon FeedIo.

using read()

read() is designed to give a brand new Feed instance or any object of your own, as long as it implements the FeedInterface interface. It takes three arguments :

• $url : URL of the RSS/Atom feed you want to read (eg: http://php.net/feed.atom)
• $feed (optional) : a FeedInterface instance. The default is a new \FeedIo\Feed instance
• $modifiedSince (optional) : the last time you read this feed. This is useful to fetch only the articles which were published after your last hit.

With a \FeedIo\FeedIo instance called $feedIo :

<?php
    // this date is used to fetch only the latest items
    $modifiedSince = new \DateTime($date);

    // the feed you want to read
    $url = 'http://host.tld/feed';

    // now fetch its (fresh) content
    $feed = $feedIo->read($url, new \Acme\Entity\Feed, $modifiedSince)->getFeed();

    foreach ( $feed as $item ) {
        echo "item title : {$item->getTitle()} \n ";
        // getMedias() returns enclosures if any
        $medias = $item->getMedias();
    }

?>

read() fetches the feed hosted at $url and removes items prior to $modifiedSince. If it is the first time you read this feed, then you must specify a date far enough in the past to keep all the items. This method does not loop until the $modifiedSince is reached, it justs performs one hit and filters the response to keep only the fresh articles.

using readSince()

readSince() helps you get a \FeedIo\Feed without creating its instance :

<?php
    // get feedio
    $feedIo = $this->container->get('feedio');

    // this date is used to fetch only the latest items
    $modifiedSince = new \DateTime($date);

    // the feed you want to read
    $url = 'http://host.tld/feed';

    // now fetch its (fresh) content
    $feed = $feedIo->readSince($url, $modifiedSince)->getFeed();
?>

Providing feeds

RssAtomBundle offers the ability to provide JSON/RSS/Atom feeds. The route will match the following pattern : /{format}/{contentId}

• {format} must be "rss" or "atom" (or whatever you want if you add the good routing rule in routing.yml)
• {contentId} is an optional argument. Use it you have several feeds

The request will be handled by StreamController, according to the following steps :

• 1 : grabs the ModifiedSince header if it exists
• 2 : creates an Options instance holding the request's parameters (contentId if it exists)
• 3 : gets the provider defined in services.yml and calls the getFeedContent(Options $options) method
• 4 : compare the feed's LastModified property with the ModifiedSince header
• 5 : if LastModified is prior or equal to ModifiedSince then the response contains only a "NotModified" header and the 304 code. Otherwise, the stream is built and sent to the client

Defining you own provider

You must give to RssAtomBundle the content you want it to display in the feed. For that, two steps :

• write a class that implements FeedProviderInterface. This class that we call a 'provider' will be in charge of building the feed.
• configure the dependency injection to make RssAtomBundle use it

FeedContentProviderInterface implementation

Your class just needs to implement the Debril\RssAtomBundle\Provider\FeedProviderInterface interface, for instance :

<?php
# src/Feed/Provider.php
namespace App\Feed;

use FeedIo\Feed;
use FeedIo\FeedInterface;
use FeedIo\Feed\Item;
use Debril\RssAtomBundle\Provider\FeedContentProviderInterface;

class Provider implements FeedProviderInterface
{
    /**
     * @param array $options
     * @return \FeedIo\FeedInterface
     * @throws \Debril\RssAtomBundle\Exception\FeedNotFoundException
     */
    public function getFeed(Request $request) : FeedInterface
    {
        // build the feed the way you want
        $feed = new Feed();
        $feed->setTitle('your title');
        foreach($this->getItems() as $item ) {
            $feed->add($item);
        }

        return $feed;
    }

    protected function getItems()
    {
        foreach($this->fetchFromStorage() as $storedItem) {
            $item = new Item;
            $item->setTitle($storedItem->getTitle());
            // ...
            yield $item;
        }
    }
    protected function fetchFromStorage()
    {
        // query the database to fetch items
    }
}

StreamController expects the getFeed()'s return value to be a FeedIo\FeedInterface instance. It can be a FeedIo\Feed or a class of your own and if so, your class MUST implement \FeedIo\FeedInterface.

You can also start from this class to save some time : App\Feed\Provider.php

<?php
interface FeedInterface extends \Iterator, NodeInterface
{
    /**
     * This method MUST return the feed's full URL
     * @return string
     */
    public function getUrl();

    /**
     * @param string $url
     * @return FeedInterface
     */
    public function setUrl($url);

    // Full source can be read in the repository .......
?>

configuration

Now, you need to configure the debril.rss_atom.provider service with the provider's class in your project's services.yml :

# config/services.yaml
parameters:
  debril.rss_atom.provider.class: 'App\Feed\Provider'

Or, if you need to build it with arguments, you can override debril.rss_atom.provider's declaration :

# config/services.yaml
services:
  debril.rss_atom.provider:
    class: App\Feed\Provider
    arguments: ["@logger", "@doctrine"]

That's it. Go to http://localhost:8000/atom, it should display your feed.

Make the StreamController answer with a 404

If the reclaimed feed does not exist, you just need to throw a FeedNotFoundException to make the StreamController answer with a 404 error. Otherwise, getFeedContent(Options $options) must return a \FeedIo\FeedInterface instance. Then, the controller properly turns the object into a XML stream.

More information on the FeedContentProviderInterface interface and how to interface rss-atom-bundle directly with doctrine can be found in the Providing Feeds section

Useful Tips

Skipping 304 HTTP Code

The HTTP cache handling can be annoying during development process, you can skip it through configuration in your app/config/config.yml file :

# config/packages/rss_atom.yaml
debril_rss_atom:
    force_refresh: true

This way, the StreamController will always display your feed's content and return a 200 HTTP code.

Private feeds

You may have private feeds, user-specific or behind some authentication.
In that case, you don't want to Cache-Control: public header to be added, not to have your feed cached by a reverse-proxy (such as Symfony AppCache or Varnish).
You can do so by setting private parameter to true in config:

# config/packages/rss_atom.yaml
debril_rss_atom:
    private: true

Adding non-standard date formats

Some feeds use date formats which are not compliant with the specifications. You can fix this by adding the format in your configuration

# config/packages/rss_atom.yaml
debril_rss_atom:
    date_formats:
      - 'Y/M/d'

Using custom Content Type header for feed generation

If you need to customize the Content-Type header of your feed you can specify the value in your configuration

# config/packages/rss_atom.yaml
debril_rss_atom:
    content_type_json: application/json
    content_type_xml: application/xhtml+xml

Going back to feed-io 3.0

Starting from version 4.1 rss-atom-bundle comes with feed-io 4 if your application depends on PHP 7.1+. If you need to use feed-io 3 instead for some reason, you can do it in composer.json :

    "debril/rss-atom-bundle": "^4.1",
    "debril/feed-io": "~3.0",

Override tip

It could happen that according to the order of the bundles registered in AppKernel, this override procedures do not work properly. This happens when a bundle is registered before rss-atom-bundle. In this case, you should use the Symfony CompilerPass as reported in the documentation.

Vendor/Bundle/VendorBundle.php:

use Vendor\Bundle\DependencyInjection\Compiler\OverrideRssAtomBundleProviderCompilerPass;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Bundle\Bundle;

class VendorBundle extends Bundle
{
    public function build(ContainerBuilder $container)
    {
        parent::build($container);
        $container->addCompilerPass(new OverrideRssAtomBundleProviderCompilerPass());
    }
}

and Vendor/Bundle/DependencyInjection/Compiler/OverrideRssAtomBundleProviderCompilerPass.php:

use Vendor\Bundle\Provider\FeedProvider;
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;

class OverrideRssAtomBundleProviderCompilerPass implements CompilerPassInterface
{
    public function process(ContainerBuilder $container)
    {
        $definition = $container->getDefinition('debril.rss_atom.provider');
        $definition->setClass(FeedProvider::class);
        $definition->addArgument(new Reference('my.service1'));
        $definition->addArgument(new Reference('my.service2'));
    }
}

You can follow either services.xml or CompilerPass but with services, you have to pay attention to bundles registration order.

Fetching the repository

Do this if you want to contribute (and you're welcome to do so):

git clone https://github.com/alexdebril/rss-atom-bundle.git

composer.phar install --dev

Unit Testing

You can run the unit test suites using the following command in the Bundle's source director:

bin/phpunit

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