Feature Flags

QUICK GATES

if(Feature::isEnabled('feature_name', $obj)) {
     <!---content---->
}
NE
@feature('my_awesome_feature',$obj)
    <p>This paragraph will be visible only if "my_awesome_feature" is enabled!</p>
@endfeature

Feature flags can be enabled at the following object in the ScholarPath App: ($user, $role, $silo, $district, $school)

Basic Usage

There are two ways you can use features: working with them globally or specifically for a specific entity.

Globally Enabled/Disabled Features

Declare a New Feature

Let's say you have a new feature that you want to keep hidden until a certain moment. We will call it "page_code_cleaner". Let's add it to our application:

Feature::add('page_code_cleaner', false);

Easy, huh? As you can imagine, the first argument is the feature name. The second is a boolean we specify to define the current status of the feature.

true stands for the feature is enabled for everyone;
false stands for the feature is hidden, no one can use it/see it;

And that's all.

Check if a Feature is Enabled

Now, let's imagine a better context for our example. We're building a CMS, and our "page_code_cleaner" is used to... clean our HTML code. Let's assume we have a controller like this one.

class CMSController extends Controller {
    public function getPage($pageSlug) {
        
        // here we are getting our page code from some service
        $content = PageService::getContentBySlug($pageSlug);
        
        // here we are showing our page code
        return view('layout.pages', compact('content'));
    }
}

Now, we want to deploy the new service, but we don't want to make it available for users, because the marketing team asked us to release it the next week. LaravelFeature helps us with this:

class CMSController extends Controller {
    public function getPage($pageSlug) {
        
        // here we are getting our page code from some service
        $content = PageService::getContentBySlug($pageSlug);
        
        // feature flagging here!
        if(Feature::isEnabled('page_code_cleaner')) {
            $content = PageCleanerService::clean($content);
        }
        
        // here we are showing our page code
        return view('layout.pages', compact('content'));
    }
}

Ta-dah! Now, the specific service code will be executed only if the "page_code_cleaner" feature is enabled.

Change a Feature Activation Status

Obviously, using the Feature class we can easily toggle the feature activation status.

// release the feature!
Feature::enable('page_code_cleaner');

// hide the feature!
Feature::disable('page_code_cleaner');

Remove a Feature

Even if it's not so used, you can also delete a feature easily with

Feature::remove('page_code_cleaner');

Warning: be sure about what you do. If you remove a feature from the system, you will stumble upon exceptions if checks for the deleted features are still present in the codebase.

Work with Views

I really love blade directives, they help me writing more elegant code. I prepared a custom blade directive, @feature:

<div>This is an example template div. Always visible.</div>

@feature('my_awesome_feature')
    <p>This paragraph will be visible only if "my_awesome_feature" is enabled!</p>
@endfeature

<div>This is another example template div. Always visible too.</div>

A really nice shortcut!

Enable/Disable Features for Specific Users/Entities

Even if the previous things we saw are useful, LaravelFeature is not just about pushing the on/off button on a feature. Sometimes, business necessities require more flexibility. Think about a Canary Release: we want to rollout a feature only to specific users. Or, maybe, just for one tester user.

Enable Features Management for Specific Users

LaravelFeature makes this possible, and also easier just as adding a trait to our User class.

In fact, all you need to do is to:

add the LaravelFeature\Featurable\Featurable trait to the User class;
let the same class implement the FeaturableInterface interface;

...

class User extends Authenticatable implements FeaturableInterface
{
    use Notifiable, Featurable;
    
...

Nothing more! LaravelFeature now already knows what to do.

Status Priority

Please keep in mind that all you're going to read from now is not valid if a feature is already enabled globally. To activate a feature for specific users, you first need to disable it.

Laravel-Feature first checks if the feature is enabled globally, then it goes down at entity-level.

Enable/Disable a Feature for a Specific User

$user = Auth::user();

// now, the feature "my.feature" is enabled ONLY for $user!
Feature::enableFor('my.feature', $user);

// now, the feature "my.feature" is disabled for $user!
Feature::disableFor('my.feature', $user);

Check if a Feature is Enabled for a Specific User

$user = Auth::user();

if(Feature::isEnabledFor('my.feature', $user)) {
    
    // do amazing things!
    
}

Other Notes

NEW ELSEFEATURE FOR BLADE DIRECTIVE LaravelFeature also provides a Blade directive to check if a feature is enabled for a specific user. You can use the @featurefor blade tags:

@featurefor('my_awesome_feature',$obj)
    <p>This paragraph will be visible only if "my_awesome_feature" is enabled!</p>
@elsefeaturefor
    <p>Something else</p>
@endfeaturefor

Advanced Things

Ok, now that we got the basics, let's raise the bar!

Enable Features Management for Other Entities

As I told before, you can easily add features management for Users just by using the Featurable trait and implementing the FeaturableInterface in the User model. However, when structuring the relationships, I decided to implement a many-to-many polymorphic relationship. This means that you can add feature management to any model!

Let's make an example: imagine that you have a Role model you use to implement a basic roles systems for your users. This because you have admins and normal users.

So, you rolled out the amazing killer feature but you want to enable it only for admins. How to do this? Easy. Recap:

add the Featurable trait to the Role model;
be sure the Role model implements the FeaturableInterface;

Let's think the role-user relationship as one-to-many one.

You will probably have a role() method on your User class, right? Good. You already know the rest:

// $role is the admin role!
$role = Auth::user()->role;

...

Feature::enableFor('my.feature', $role);

...

if(Feature::isEnabledFor('my.feature', $role)) {

    // this code will be executed only if the user is an admin!
    
}

Scan Directories for Features

One of the nice bonuses of the package that inspired me when making this package, is the ability to "scan" views, find @feature declarations and then add these scanned features if not already present on the system.

I created a simple artisan command to do this.

$ php artisan feature:scan

The command will use a dedicated service to fetch the resources/views folder and scan every single Blade view to find @feature directives. It will then output the search results.

Try it, you will like it!

Credits

License

The MIT License (MIT). Please see License File for more information.