Authorization: Understanding Policies in Laravel

Controlling what users can or cannot do in your application is one of the most essential things you'll need to do when building real-world applications.

For example, in a todo application, you don't want a user to be able to edit or delete other users' todos.

In this article, you will learn one of the seamless ways to do this in Laravel by using policies to control what users can do by building a simple todo application.

To follow along with this tutorial, you need to have a basic understanding of Laravel and its application structure.

Create a Base Application

Run the following command to create a new Laravel application in your desired folder and move into it:

composer create-project laravel/laravel todo-app && cd todo-app

Next, run the following command to install Laravel Breeze:

php artisan breeze:install

Breeze will scaffold your new application with authentication so your users can register, log in, log out, and view their personalized dashboards.

After that, compile your application assets by running the following commands:

npm install && npm run dev

Laravel comes with the file-based SQLite database by default, so the next thing you need to do is connect your application database file to a database viewer like TablePlus or any other one you like.

After connecting your database to the viewer, run the following commands to migrate the available tables into your database:

php artisan migrate

Once that is done, run the following command to view your application in the browser:

php artisan serve

You should now see your new Laravel application at localhost:8000 looking like this:

You can now go to the register page to create a user and access the dashboard, which is the entire application at this point.

Model Setup

Models in Laravel are used to control database tables. Use the following command to create a Todo model in the App/Models folder:

php artisan make:model Todo

Next, inside the newly created file, replace the Todo class with the following code:

class Todo extends Model
{
    use HasFactory;

    protected $fillable = [
        'title',
        'description',
        'completed',
        'user_id'
    ];

    public function user()
    {
        return $this->belongsTo(User::class);
    }
}

The code above will enable users to submit a form with the $fillable properties; it also defines the relationship between a user and a Todo; in this case, a todo belongs to a user. Let's complete the relationship setup by adding the following code to the App/Models/User.php file:

    public function todos()
    {
        return $this->hasMany(Todo::class);
    }

The code above will connect the User model to the Todo model so that it can have many to-dos.

Migration Setup

Migrations in Laravel are used to specify what should be in a database table. Run the following command to create a migration inside the database/migrations folder:

composer create-project laravel/laravel todo-app && cd todo-app

Next, replace the up function in the new file with the following that will add the todo table to the database with the id, user_id, title, description, completed, and timestamp columns:

php artisan breeze:install

Next, run the following command to add the todos table to the database:

npm install && npm run dev

Policy Setup

Policies in Laravel allow you to define who can do what with a particular resource, in this case, todos.

Let's see how that works by generating a TodoPolicy inside the App/Policies folder using the following command:

php artisan migrate

Next, in the newly created TodoPolicy file, replace the TodoPolicy class with the following code:

php artisan serve

The code above specifies that a user can create a todo, but can only view, update, or delete a todo that belongs to them.

Next, let's set up the controller in the next section.

Controller Setup

Controllers in Laravel control the app's functionality for a particular resource. Run the following command to generate a TodoController inside the App/Http/Controllers:

php artisan make:model Todo

Add the following code to the top of the newly created TodoController file to import the Todo model for database operations and Gate class for authorization:

class Todo extends Model
{
    use HasFactory;

    protected $fillable = [
        'title',
        'description',
        'completed',
        'user_id'
    ];

    public function user()
    {
        return $this->belongsTo(User::class);
    }
}

Index Method

Replace the index method with the following code that fetches and returns all the logged-in users' todos:

    public function todos()
    {
        return $this->hasMany(Todo::class);
    }

The Gate::authorize method verifies that the user is logged in using the viewAny policy method you defined in the previous section.

Create Method

Replace the create method with the following code that verifies the user is signed in before returning the create todo form to the user so they can create todos:

php artisan make:migration create_todos_table

Store Method

Replace the store method with the following code that checks if the user can create a todo, validates the request, creates the todo, and redirects the user to the todo list page:

   public function up(): void
    {
        Schema::create('todos', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id')->constrained()->onDelete('cascade');
            $table->string('title');
            $table->text('description')->nullable();
            $table->boolean('completed')->default(false);
            $table->timestamps();
        });
    }

Edit Method

Replace the edit method with the following code that verifies the user can edit that todo before returning the edit todo form populated with the selected todo to the user so they can edit it:

php artisan migrate

Update Method

Replace the update method with the following code that checks if the user can update the todo, validates the request, updates the selected todo, and redirects the user to the todo list page:

php artisan make:policy TodoPolicy --model=Todo

Destroy Method

Replace the destroy method with the following code that checks if the user can delete the todo, deletes it, and redirects the user to the todo list page:

class TodoPolicy
{
    /**
     * Determine if the user can view any todos.
     */
    public function viewAny(User $user): bool
    {
        return true;
    }

    /**
     * Determine if the user can view the todo.
     */
    public function view(User $user, Todo $todo): bool
    {
        return $user->id === $todo->user_id;
    }

    /**
     * Determine if the user can create todos.
     */
    public function create(User $user): bool
    {
        return true;
    }

    /**
     * Determine if the user can update the todo.
     */
    public function update(User $user, Todo $todo): bool
    {
        return $user->id === $todo->user_id;
    }

    /**
     * Determine if the user can delete the todo.
     */
    public function delete(User $user, Todo $todo): bool
    {
        return $user->id === $todo->user_id;
    }
}

Your TodoController file should now look like this:

composer create-project laravel/laravel todo-app && cd todo-app

Views Setup

Now that your TodoController methods are all set, you can now create the views for your applications by creating a new todos folder inside the resources/views folder. After that, create create.blade.php, edit.blade.php, index.blade.php files in the new todos folder.

Index View

Paste the following code inside the index.blade.php:

php artisan breeze:install

Create View

Paste the following code inside the create.blade.php:

npm install && npm run dev

Edit View

Paste the following code inside the edit.blade.php:

php artisan migrate

Routes Setup

Handling routes for your TodoController is relatively straightforward using the resource method in Laravel. Do that by adding the following code to the end of the routes/web.php folder like so:

php artisan serve

The code above uses the auth middleware to protect the todos resource. You should now be able to visit the following routes in your application after being logged in:

• /todos: List all users' todos
• /todos/create: Shows the form for creating todos
• /todos/edit/1: Shows the form for editing a todo with the given id; 1 in this case.

You can now create, edit, and delete todos, BUT only as a logged-in user and the owner of the selected todos in the case of editing and deleting.

Conclusion

And that's it! You have just created a realistic todo application that allows users to create, view, edit, and delete ONLY their own todos. Please let me know if you have any corrections, suggestions, or questions in the comments!

Finally, remember to follow me here on Dev, LinkedIn, and Twitter. Thank you so much for reading, and I'll see you in the next one!

The above is the detailed content of Authorization: Understanding Policies in Laravel. For more information, please follow other related articles on the PHP Chinese website!