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FOSUserBundle <3's Guard Authenticators

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We now understand that FOSUserBundle just gives us a nice User class and some routes & controllers for registration, reset password, edit profile and a few other things. The bundle does not provide any authentication. Open app/config/security.yml. The form_login authentication mechanism we're using is core to Symfony itself, not this bundle.

So, one of the questions we get a lot is: how can I use Guard authentication with FOSUserBundle? It turns out, it's simple! Guard authentication and FOSUserBundle solve different problems, and they work together beautifully. Teamwork makes the dream work!

But, why would you want to use Guard authentication with FOSUserBundle? Well, as easy as form_login is, it's a pain to customize. Guard is more work up front, but gives you a lot more control. You can also use Guard to add some sort of API authentication on top of form_login.

Creating the Authenticator

Let's replace form_login with a more flexible Guard authenticator. At the root of our project, you should have tutorial/ directory with a file called LoginFormAuthenticator.php. In src/AppBundle, create a new directory called Security and paste that file here.

// ... line 2
namespace AppBundle\Security;
// ... lines 4 - 19
class LoginFormAuthenticator extends AbstractFormLoginAuthenticator
// ... lines 22 - 101

This LoginFormAuthenticator is almost an exact copy of the authenticator we created in our Symfony Security tutorial. I've just added CSRF token checking - since our HTML login form has a CSRF token in it - and made a few other minor tweaks. For example at the bottom, I updated the login route name to use the one from FOSUserBundle.

The authenticator is very straightforward: It looks for the submitted _username and _password fields from the login form. It doesn't care if you built that login form yourself, or if it comes from FOSUserBundle. Then, it queries for your User object by email only and checks to see if the password is valid. Obviously you can write your authenticator to do anything.

Registering the Authenticator

To get this to work, like all authenticators, we need to register it as a service. I'll add, set the class to LoginFormAuthenticator and use autowire: true.

32 lines | app/config/services.yml
// ... lines 1 - 5
// ... lines 7 - 28
class: AppBundle\Security\LoginFormAuthenticator
autowire: true

Copy that service ID. Then open app/config/security.yml. Ok, let's comment-out form_login entirely. And instead, add guard, authenticators, then paste the service ID.

38 lines | app/config/security.yml
// ... lines 1 - 2
// ... lines 4 - 12
// ... lines 14 - 18
// ... lines 20 - 27
# form_login:
# csrf_token_generator: security.csrf.token_manager
// ... lines 34 - 38

That's it! FOSUserBundle doesn't care who or what is processing the login form submit.

Let's try it! Click log out, click login and login with Yea, this does still say "Username", but we know that our authenticator actually logs us in via email. So, we'll want to tweak that language. Use the password admin and... boom!

Congrats! You just used a Guard authenticator with FOSUserBundle. Wasn't that nice? You should feel empowered to use FOSUserBundle because you want things like a registration page or reset password system. But, you can still take control of your actual login mechanism and do whatever the heck you want.

The last part of this bundle that you'll need to customize are the emails: the reset password email and the registration confirmation email, if you want to send that one. The docs are good on this topic, and it's mostly a matter of overriding templates... which we already mastered.

All right guys, go use FOSUserBundle to quickly bootstrap your site! As long as you understand what it does... and does not give you, it's awesome. Seeya next time!