How to implement permission-based display and hiding of page elements in Laravel

In Laravel, it is a common requirement to implement permission-based display and hiding of page elements. This article will introduce how to use Laravel's permission management library "spatie/laravel-permission" to implement the function of dynamically rendering page elements. At the same time, in order to better illustrate the problem, this article will write a simple example program.

1. Install laravel-permission

First, you need to install the "spatie/laravel-permission" composer package in the Laravel project. Use the following command to install:

composer require spatie/laravel-permission

After installation, you need to run migration to create the relevant permission management table:

php artisan vendor:publish --provider="SpatiePermissionPermissionServiceProvider" --tag="migrations"

php artisan migrate

2. Define roles and permissions

In this example , we will define two roles, namely "Administrator" and "General User", and give the administrator the permission to view all data.

First, you need to add the configuration of the role and permission model in the config/auth.php file:

'providers' => [
    'users' => [
        'driver' => 'eloquent',
        'model' => AppModelsUser::class,
    ],

    'roles' => [
        'driver' => 'eloquent',
        'model' => SpatiePermissionModelsRole::class,
    ],

    'permissions' => [
        'driver' => 'eloquent',
        'model' => SpatiePermissionModelsPermission::class,
    ],
],

Then, add the relationship with the role and permission in the User model:

namespace AppModels;

use IlluminateDatabaseEloquentFactoriesHasFactory;
use IlluminateFoundationAuthUser as Authenticatable;
use SpatiePermissionTraitsHasRoles;

class User extends Authenticatable
{
    use HasFactory, HasRoles;

    //...
}

Then you can define roles and permissions in Seeder:

use IlluminateDatabaseSeeder;
use SpatiePermissionModelsPermission;
use SpatiePermissionModelsRole;

class RolesAndPermissionsSeeder extends Seeder
{
    public function run()
    {
        //创建角色
        Role::create(['name' => 'admin']);
        Role::create(['name' => 'user']);

        //创建权限
        Permission::create(['name' => 'view_all_data']);

        //管理员拥有所有权限
        Role::findByName('admin')->givePermissionTo(Permission::all());
    }
}

3. Authorization and authentication

Next, use the authorize() method in the controller to determine whether the user Have specific permissions. For example, the following index method requires the "view_all_data" permission:

public function index()
{
    $this->authorize('view_all_data');
    //...
}

In addition, in the view, you can use the can() method to determine whether the current user has a certain permission. For example, in the following code, the "View All Data" button will be displayed only if the user has the "view_all_data" permission:

@if(auth()->user()->can('view_all_data'))
    <button>查看所有数据</button>
@endif

If you want more fine-grained control, you can use the role() method. Determine whether the user has a certain role. For example, in the following code, the "Administrator Menu" will be displayed only when the user has the "admin" role:

@if(auth()->user()->hasRole('admin'))
    <menu>管理员菜单</menu>
@endif

4. Dynamically rendering page elements

Sometimes, the Certain elements need to be rendered dynamically based on the current user's role or permissions. For example, you can set that only administrators can see the "Delete" button:

@if(auth()->user()->can('delete_data'))
    <button>删除</button>
@endif

However, if there are multiple elements that need to be dynamically rendered based on permissions, then each element must be judged individually, which will lead to code duplication and maintenance. Increased costs. At this time, you can encapsulate this function into a Blade command and let it accept a permission name as a parameter:

Blade::directive('can', function ($expression) {
    return "<?php if(auth()->user()->can({$expression})): ?>";
});

Blade::directive('endcan', function () {
    return "<?php endif; ?>";
});

Using this command, you can dynamically render page elements in the following way:

@can('delete_data')
    <button>删除</button>
@endcan

In this way, the code becomes more concise and clear.

Summary

By using Laravel's permission management library "spatie/laravel-permission", we can easily implement permission-based display and hiding of page elements. At the same time, encapsulating dynamically rendered code into Blade instructions can further simplify the code and improve the readability and maintainability of the code.

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