Using when() in the Laravel query builder

example.php

<?php

namespace App\Http\Controllers;

use App\Post;
use Illuminate\Http\Request;

class PostsController extends Controller
{
    public function index(Request $request)
    {
        $statusFilter = $request->get('status_filter');
        
        $posts = Post::when($statusFilter, function($builder) use ($statusFilter) {
            // This where clause is only applied when the `status_filter` field was present in the request.
            return $builder->where('status', $statusFilter);
        })->get();
        
        // Usage with a default (available since v5.3.10)
        $posts = Post::when($statusFilter, function($builder) use ($statusFilter) {
            // This where clause is only applied when the `status_filter` field was present in the request.
            return $builder->where('status', $statusFilter);
        }, function($builder) {
            // This where clause is only applied when the `status_filter` field was NOT present in the request.
            return $builder->where('status', 'published');
        })->get();
        
        return $posts;
    }
}