The Symfony2 DependencyInjection Component has made my life and work as a developer a lot easier. Choosing the right way to use it however can be a bit difficult sometimes. Knowing what a/the service container can do, helps a lot, and also thinking about how you would do it with just PHP can put you back on track. To be able to recognize some problems related to dependency injection in your own code, I will describe a few “dependency injection smells” below (a term derived from “code smells”, used by Kent Beck, Martin Fowler and the likes).

Writing PHP code with PHP is not very easy. You are constantly switching between the context of the code that generates the code and the code that is to be generated (see, you lost it already!). Some variables are available in the first context, some in the second, and you will have to pass the right values in the right way. One of the areas in Symfony-land where you will have to do these things is when you extend Twig by hooking into the parser and defining your own tags. A tag for example is the “for” in

Symfony2 provides multiple ways of blocking, providing or modifying the response. You can:

1. Intercept each request by listening to the kernel.request event and set the response directly on the event (which will effectively skip execution of a controller)

2. Modify the controller or its arguments by listening to the kernel.controller event, then calling setController on the event object and modifying the attributes of the Request object.

3. Change the response rendered by a controller, by listening to the kernel.response event.

A Symfony2 application provides developers with several ways to manipulate its behavior. First of all, it is possible to define different environments for different scenarios:

• A “prod” environment to be used when the web application is on the live server

• A “dev” environment used while developing the application. Generated parts of the application are regenerated when one of the files the generation was based on has changed

• A “test” environment used when running functional unit tests/li>

These days, good PHP object-oriented libraries are all around and easily available. To me, it is actually thrilling to be part of this flourishing community, while working with Symfony2 and blogging about the Framework, the Components and their neighbors (like Silex). It seems like everything is made for contributing to this nice and friendly environment, with tools like GitHub (online collaboration), Composer (dependency management), Packagist (package archive) and Travis CI (continuous integration).

Still, to me, contributing felt like too big a step to take right now. Until a few weeks ago, when I was looking for something I needed (a PHP client for the Microsoft Translator API) and could not find a decent solution. I decided to make it myself, and share it online. Below I’ve written down my steps. As you can see, they are very easy and would require just a bit of extra time. So, take from it what you need, and start contributing!

In my previous post I wrote about uploading files to GridFS. Therefor I created a MongoDB Document with a $file property annotated with @MongoDB\File. Because I am using ORM entities more often then ODM documents, I was looking for a seamless way to access a Document from an Entity.

Because it isn’t possible to define a direct relationship between an Entity and a Document I thought it would be a solid solution to create a custom field type. By defining a custom field type I can control the way the reference to the Document will be stored and at the same time I will be able to restore the reference when retrieving the field. The steps needed to create a custom field type for ORM entities are very similar to the post of Matthias on how to create custom field types for ODM documents.

Almost at the same time, I silently celebrate the first birthday of my blog. My first article appeared a little over a year ago. It is great to see how Symfony2 has become more and more popular during these twelve months. Your comments and visits encourage me to keep posting articles. So, thank you all! And thanks, Dennis, for contributing.

GridFS is a specification for storing large files in MongoDB. In this post I will explain how you can easily upload a file to GridFS and then retrieve it from the database to serve it to the browser.

Just a quick post…

What seems to be missing from the DoctrineMongoDBBundle is a ParamConverter service which resolves request attributes to controller arguments by fetching a Document using the MongoDB DocumentManager. For entities, this would work:

/**
 * @Route("/blog/{id}
 */
public function showAction(Post $post)
{
    // $post will be the entity Post with the "id" taken from the route pattern
}

This works because of the DoctrineParamConverter, which is registered by default by the SensioFrameworkExtraBundle. But only for Doctrine ORM, and not for Doctrine MongoDB ODM. As Christophe Coevoet mentioned when someone tried to implement this missing feature, it can be added easily by yourself, without writing any PHP code, though it might not be so clear how to accomplish this. Still, the only thing you have to do is add a service to your services.xml file:

With Doctrine MongoDB ODM it is possible to add custom field types and define how its values should be converted from and to the database. But type management in the MongoDB ODM currently suffers from several design flaws. This makes it non-trivial to create a custom type, especially when your type conversion has any dependencies. This is how it works:

use Doctrine\ODM\MongoDB\Mapping\Types\Type;

Type::registerType('custom', 'Matthias\CustomTypeBundle\MongoDB\Type\CustomType');

$type = Type::getType('custom');
// $type is an instance of Matthias\CustomTypeBundle\MongoDB\Type\CustomType

As you will understand, the Type class is both a Registry and a Factory. Yet, it only allows you to define a type as a class, not as an object. This means: no constructor arguments can be passed. When using Symfony2, this implies that types can not be services, and you can use neither constructor nor setter injection.

Authorization

When any of the authentication providers has verified the still unauthenticated token, an authenticated token will be returned. The authentication listener should set this token directly in the SecurityContext using its setToken() method.

From then on, the user is authenticated, i.e. means identified. Now, other parts of the application can use the token to decide whether or not the user may request a certain URI, or modify a certain object. This decision will be made by an instance of AccessDecisionManagerInterface.