@can Laravel Blade

Valerio Barbera

The @can Laravel Blade directive is a simple way to manage user permissions directly in your templates. It works with Laravel’s authorization system (policies and gates) to hide or show content based on user roles or actions. Here’s what you need to know:

What It Does: Checks if a user has permission to perform an action, like editing or deleting a post.
Why Use It: Keeps your views secure, clean, and consistent by handling permissions in one place.
How to Use: Wrap UI elements with @can or @cannot to restrict access. Example:
```
@can('update', $post)
    <button>Edit Post</button>
@endcan
```
Advanced Features: Use @canany for multiple permissions, pass extra parameters for complex checks, and handle unauthenticated users securely.

Quick Overview

Setup: Define policies using php artisan make:policy, register them in AuthServiceProvider, and map methods like update or delete.
Directives: Use @can, @cannot, and @canany in your templates for conditional rendering.
Tips: Ensure correct parameter matching between directives and policy methods, and use Gate::before for admin overrides.

Laravel’s @can makes authorization seamless and keeps your views secure. Dive into the article for step-by-step guidance and examples.

Creating Policies for @can

Create Policies with Artisan

Laravel makes policy creation easier with its Artisan command. To generate a policy with methods tailored to a specific model, run:

php artisan make:policy PostPolicy --model=Post

This command creates a policy file with methods for common actions on the model.

Define Policy Methods

Policy methods take the authenticated user as the first argument and usually the model instance as the second. Here’s an example of a PostPolicy:

class PostPolicy
{
    public function delete(User $user, Post $post)
    {
        return $user->id === $post->user_id || $user->isEditor();
    }
}

In this case, the delete method allows post deletion if the user owns the post or has editor privileges.

Register Policies

Laravel provides two ways to register your policies:

1. Manual Registration
Manually map policies to models in AuthServiceProvider.php:

use App\Models\Post;
use App\Policies\PostPolicy;

public function boot()
{
    $this->registerPolicies();
    Gate::policy(Post::class, PostPolicy::class);
}

2. Wildcard Default Policy
Set a default policy for all models using a wildcard:

protected $policies = [
    '*' => 'App\Policies\DefaultPolicy',
];

To give administrators full access while maintaining other permissions, you can use a Gate::before check:

Gate::before(function ($user, $ability) {
    return $user->isAdmin() ? true : null;
});

After registering, these policies enable the use of @can directives in your Blade templates.

Implementing @can in Templates

Once your policies are set up, you can use them directly in your Blade templates to manage access control. Here’s how:

Basic @can Usage

The @can directive checks if a user has permission for a specific action. For example:

@can('update', $post)
    <a href="{{ route('posts.edit', $post) }}">Edit</a>
@elsecan('create-post')
    <button>New Post</button>
@endcan

In this snippet, the user can either edit the post or, if not, see the option to create a new one.

Using Multiple Parameters in @can

Sometimes, you need to pass extra data to your policy methods. Here’s an example:

@can('update', [$post, 'draft'])
    <button>Save Draft</button>
    <button>Publish</button>
@endcan

The associated policy method would look like this:

public function update(User $user, Post $post, string $status)
{
    return $user->id === $post->user_id && $status === 'draft';
}

This approach gives you flexibility to handle more complex scenarios.

@cannot and @canany Directives

For cases where you want to check if a user cannot perform an action, use @cannot:

@cannot('delete', $post)
    <div>Only post owners can delete this content.</div>
@endcannot

If you need to check multiple permissions, use @canany:

@canany(['publish', 'feature', 'promote'], $post)
    @can('publish', $post)<button>Publish</button>@endcan
    @can('feature', $post)<button>Feature</button>@endcan
@endcanany

This is useful for displaying options based on different permissions.

Handling Unauthenticated Users

To handle unauthenticated users in your templates, you can set your policy methods to accept nullable arguments:

public function view(?User $user, Post $post)
{
    if ($user === null) {
        return $post->is_public;
    }
}

This ensures that your templates remain secure, even when dealing with guests.

Advanced @can Features

Laravel’s @can directive provides more than just basic permission checks. It enables sophisticated authorization patterns that improve both security and code organization. Let’s dive into some practical implementations.

Policy Filters for Admins

You can use the before method in policies to allow admin overrides:

public function before($user, $ability)
{
    return $user->isAdmin(); // Grants full access
}

This method ensures admins have unrestricted access. Additionally, Laravel supports both instance-level and class-level model authorization, offering flexibility in how permissions are applied.

Simplify Logic with @canany

The @canany directive is perfect for scenarios where multiple permissions need to be checked in your templates:

@canany(['publish', 'schedule', 'feature'], $article)
    <!-- Action buttons -->
@else
    <p>No management permissions</p>
@endcanany

This reduces clutter in your templates and makes permission checks more readable while handling multiple conditions efficiently.

Model-Based Authorization

Laravel’s model-based authorization allows two main approaches:

Type	Syntax	Use Case
Instance	`@can('update', $post)`	For a specific item
Class	`@can('create', Post::class)`	For general actions

For more complex scenarios involving multiple models, you can define custom policy methods. For example:

public function transferPost(User $user, Post $post, Category $category)
{
    return $user->id === $post->user_id && 
           $category->allows_transfers && 
           $post->status === 'published';
}

In your templates, pass the required parameters explicitly:

@can('transferPost', [$post, $targetCategory])
    <button class="transfer-btn">Transfer to {{ $targetCategory->name }}</button>
@endcan

This method keeps your templates clean and supports complex, multi-model authorization logic with ease.

Fix Common @can Issues

Even with a well-configured policy setup, developers can still face challenges when using @can. Here’s how to tackle some of the most common issues:

Fix Policy Detection

If policies aren’t being detected, the problem often lies in how they’re implemented or configured. Here’s an example of a properly named policy:

// Example of correct policy naming
class PostPolicy // This matches the Post model
{
    public function view(User $user, Post $post)
    {
        return $user->id === $post->user_id;
    }
}

To make sure policies are detected correctly:

Place your policies in the app/Policies directory.
Clear the configuration cache by running:
```
php artisan config:clear
```

Correct Parameter Errors

Mismatched parameters between @can directives and policy methods can lead to unexpected results. Here are some common issues and their fixes:

Problem	Incorrect Usage	Correct Usage
Parameter Count	`@can('update', $post, $extra)`	`@can('update', $post)`
Model Binding	`@can('view', $id)`	`@can('view', $post)`
Type Mismatch	`@can('publish', $postArray)`	`@can('publish', $post)`

Monitor with Inspector

Inspector is a tool that provides real-time tracking for authorization issues. To monitor @can usage with Inspector, update the configuration file:

// Update config/inspector.php
return [
    'monitoring' => [
        'authorization' => true,
        'policies' => true
    ]
];

Inspector’s dashboard allows you to keep an eye on:

Failed authorization attempts
Policy execution times
Authorization-related exceptions

For detailed setup instructions, refer to Inspector’s Laravel documentation.

Summary

Key Points

Here’s a breakdown of the main principles for secure and efficient template authorization, building on the earlier implementation steps:

Policy Implementation
These steps focus on setting up policies to support template authorization effectively:

Set up model-specific policies with detailed methods, registered via AuthServiceProvider.
Define specific methods like view, create, update, and delete within your policies.
Register these policies in AuthServiceProvider to enable automatic resolution.

Template Integration
When working within templates:

Use @can/@cannot directives with model instances for authorization checks, and rely on @canany for handling multiple conditions.
Avoid overloading templates with too many authorization checks.

Best Practices
To maintain clarity and consistency:

Follow naming conventions like pairing models with their corresponding policies (e.g., Post → PostPolicy).
Ensure parameter types are properly validated.

Further Learning

If you want to dive deeper into Laravel authorization beyond Blade templates, consider exploring:

Core Laravel Features

Use Gates as an additional method for handling authorization .

For more details, refer to these resources:

Laravel’s official authorization documentation.
Community discussions on Laravel’s GitHub.