Using Trait in Laravel

Recently I got a chance to build a CRM system using Laravel and Backpack.

When building the CRM, I learned how to use Trait in PHP. Trait is a feature introduced in PHP 5.4 that let you create a mixin class which can be added to any other class you want. It can’t be instantiated or extended, you simply use it. Literally, you just use it, and everything in it becomes a part of the class that uses it.

In my case I wanted to setup permissions to each CRUD functionality based on user’s role. If the role has read permission, I want to enable list and show access in Backpack. If the role has write permission, I want to enable create and update, so on and so forth.

In Backpack you can setup the access in a CRUD controller by doing:

$this->crud->allowAccess(['list', 'show']);
$this->crud->denyAccess(['create', 'update', 'delete']);

Considering that I have 5 CRUD controllers for all my models, I don’t want to repeat this code in every controller.

So I figured that I can do this using a Trait class.

Simply created a Trait class app/Traits/Access.php. And in the Trait class I can do this:

<?php

namespace App\Traits;

use Illuminate\Support\Facades\Auth;

trait Access
{
    public function setupAccess()
    {
        $user = Auth::user();

        $permissions = [];
        foreach ($user->roles as $role) {
            foreach ($role->permissions()->pluck('name') as $permission) {
                if (!in_array($permission, $permissions)) {
                    array_push($permissions, $permission);
                }
            }
        }

        if (in_array('read', $permissions)) {
            $this->crud->allowAccess(['list', 'show']);
        } else {
            $this->crud->denyAccess(['list', 'show']);
        }

        //... setup other permissions
    }
}

What’s cool (and weird in some way) about the Trait class is that I can just assume $this->crud is available to me, because I will be using the Trait in my CRUD controller, and everything that the CRUD controller has will be available to the Trait class.

Then in my controller I only need to import the Trait, use it then call the method in the constructor, or in Backpack’s case, in the setup method:

use App\Traits\Access;

class UserCrudController extends CrudController
{
    use Access;

    public function setup()
    {
        $this->setupAccess();
    }
    // ... other things
}

As a result, I can do the same thing in other controllers without repeating the same code in every controller.

It is quite simple but also pretty powerful.