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Morcos Gad
Morcos Gad

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Eloquent Performance - N+1 Query Problems - Laravel

I knew that this problem N+1 is one of the problems that affect the performance of my project and I found this article that contains the reasons https://laravel-news.com/laravel-n1-query-problems and solution to this problem and I wanted to share it with you because of the importance of this topic

Four cases to clarify the problem and solve it

  • Case 1. "Regular" N+1 Query
// app/Models/Book.php
class Book extends Model
{
    public function author()
    {
        return $this->belongsTo(Author::class);
    }
}
// Then, in some Controller:
$books = Book::all();
foreach ($books as $book) {
    echo $book->author->name;
}
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fix

// Instead of
$books = Book::all();
// You should do
$books = Book::with('author')->get();
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  • Case 2. Two Important Symbols
public function index()
{
    $authors = Author::with('books')->get();
    return view('authors.index', compact('authors'));
}

// Blade
@foreach($authors as $author)
    <tr>
        <td>{{ $author->name }}</td>
        <td>{{ $author->books()->count() }}</td>
    </tr>
@endforeach
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So, the method of relation would query the database for each author. But if you load the data, without () symbols, it will successfully use the eager loaded data $author->books
fix

// Controller
$authors = Author::withCount('books')->get();
// Blade
{{ $author->books_count }}
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  • Case 3. "Hidden" Relationship in Accessor
// Controller
public function index()
{
    $authors = Author::all();
    return view('authors.index', compact('authors'));
}

// Blade
@foreach($authors as $author)
    <tr>
        <td>{{ $author->name }}</td>
        <td>{{ $author->is_active ? 'Yes' : 'No' }}</td>
    </tr>
@endforeach
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That "is_active" is defined in the Eloquent model

use Illuminate\Database\Eloquent\Casts\Attribute;
class Author extends Model
{
    public function isActive(): Attribute
    {
        return Attribute::make(
            get: fn () => $this->books->count() > 0,
        );
    }
}
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  • Case 4. Be Careful with Packages

Laravel has a great ecosystem of packages, but sometimes it's dangerous to use their features "blindly". You can run into unexpected N+1 queries if you're not careful.

  • The Built-In Solution Against N+1 Query

since Laravel 8.43, the framework https://laravel-news.com/disable-eloquent-lazy-loading-during-development

In addition to the Laravel Debugbar for inspection, you can add a code to the prevention of this problem

You need to add two lines of code to app/Providers/AppServiceProvider.php

use Illuminate\Database\Eloquent\Model;
class AppServiceProvider extends ServiceProvider
{
    public function boot()
    {
        Model::preventLazyLoading(! app()->isProduction());
    }
}
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Now, if you launch any page that contains an N+1 Query problem, you will see an error page

I have explained only the important points, but to go deeper, the article must be increased and benefited from.

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