Generate PHP class instances populated with dummy data using Faker

---

Index

• Requirements
• Installation
• Introduction
• Setup
  • HasFactory Trait
  • Class Factory
• Usage
  • Factory States
  • Factory Callbacks
  • Factory Sequences
  • Factory Collections

Requirements

• PHP >= 8.0

Installation

You can install the package via composer:

composer require directorytree/dummy

Introduction

Consider you have a class representing a restaurant reservation:

namespace App\Data;

class Reservation
{
    /**
     * Create a new reservation instance.
     */
    public function __construct(
        public string $name,
        public string $email,
        public DateTime $date,
    ) {}
}

To make dummy instances of this class during testing, you have to manually populate it with dummy data.

This can quickly get out of hand as your class grows, and you may find yourself writing the same dummy data generation code over and over again.

Dummy provides you with a simple way to generate dummy instances of your classes using a simple API:

// Generate one instance:
$reservation = Reservation::factory()->make();

// Generate multiple instances:
$collection = Reservation::factory()->count(5)->make();

Setup

Dummy provides you two different ways to generate classes with dummy data.

HasFactory Trait

The HasFactory trait is applied directly to the class you would like to generate dummy instances of.

To use the HasFactory trait, you must implement the toFactoryInstance and getFactoryDefinition methods:

Note

The HasFactory trait does not provide you the capability of defining state methods or callbacks. If you need this functionality, you should define a separate Factory class instead.

namespace App\Data;

use DateTime;
use Faker\Generator;
use DirectoryTree\Dummy\HasFactory;

class Reservation
{
    use HasFactory;
    
    /**
     * Create a new reservation instance.
     */
    public function __construct(
        public string $name,
        public string $email,
        public DateTime $date,
    ) {}
    
    /**
     * Define the factory's default state.
     */
    protected function getFactoryDefinition(Generator $faker): array
    {
        return [
            'name' => $faker->name(),
            'email' => $faker->email(),
            'datetime' => $faker->dateTime(),
        ];
    }
    
    /**
     * Create a new instance of the class using the factory definition.
     */
    protected static function toFactoryInstance(array $attributes): static
    {
        return new static(
            $attributes['name'],
            $attributes['email'],
            $attributes['datetime'],
        );
    }
}

Once implemented, you may call the Reservation::factory() method to create a new dummy factory:

$factory = Reservation::factory();

Class Factory

If you need more control over the dummy data generation process, you may use the Factory class.

The Factory class is used to generate dummy instances of a class using a separate factory class definition.

To use the Factory class, you must extend it with your own and override the definition and generate methods:

namespace App\Factories;

use App\Data\Reservation;
use DirectoryTree\Dummy\Factory;

class ReservationFactory extends Factory
{
    /**
     * Define the factory's default state.
     */
    protected function definition(): array
    {
        return [
            'name' => $this->faker->name(),
            'email' => $this->faker->email(),
            'datetime' => $this->faker->dateTime(),
        ];
    }
    
    /**
     * Generate a new instance of the class.
     */
    protected function generate(array $attributes): Reservation
    {
        return new Reservation(
            $attributes['name'],
            $attributes['email'],
            $attributes['datetime'],
        );
    }
}

Usage

Once you've defined a factory, you can generate dummy instances of your class using the make method:

// Using the trait:
$reservation = Reservation::factory()->make();

// Using the factory class:
$reservation = ReservationFactory::new()->make();

To add or override attributes in your definition, you may pass an array of attributes to the make method:

$reservation = Reservation::factory()->make([
    'name' => 'John Doe',
]);

To generate multiple instances of the class, you may use the count method:

This will return a Illuminate\SupportCollection instance containing the generated classes.

$collection = Reservation::factory()->count(5)->make();

Factory States

State manipulation methods allow you to define discrete modifications that can be applied to your dummy factories in any combination.

For example, your App\Factories\Reservation factory might contain a tomorrow state method that modifies one of its default attribute values:

class ReservationFactory extends Factory
{
    // ...

    /**
     * Indicate that the reservation is for tomorrow.
     */
    public function tomorrow(): Factory
    {
        return $this->state(function (array $attributes) {
            return ['datetime' => new DateTime('tomorrow')];
        });
    }
}

Factory Callbacks

Factory callbacks are registered using the afterMaking method and allow you to perform additional tasks after making or creating a class. You should register these callbacks by defining a configure method on your factory class. This method will be automatically called when the factory is instantiated:

class ReservationFactory extends Factory
{
    // ...
    
    /**
     * Configure the dummy factory.
     */
    protected function configure(): static
    {
        return $this->afterMaking(function (Reservation $reservation) {
            // ...
        });
    }
}

Factory Sequences

Sometimes you may wish to alternate the value of a given attribute for each generated class.

You may accomplish this by defining a state transformation as a sequence:

Reservation::factory()
    ->count(3)
     ->sequence(
        ['datetime' => new Datetime('tomorrow')],
        ['datetime' => new Datetime('next week')],
        ['datetime' => new Datetime('next month')],
    )
    ->make();

Factory Collections

By default, when making more than one dummy class, an instance of Illuminate\Support\Collection will be returned.

If you need to customize the collection of classes generated by a factory, you may override the collect method:

class ReservationFactory extends Factory
{
    // ...
    
    /**
     * Create a new collection of classes.
     */
    public function collect(array $instances = []): ReservationCollection
    {
        return new ReservationCollection($instances);
    }
}