Make Laravel's eloquent model factories stateful.

StatefulFactory.php

<?php

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Arr;

trait StatefulFactory
{
    /**
     * Set factory state, which is not persisted to the database.
     * 
     * Factory state is wiped using clearFactoryState() method.
     * 
     * @param array $state
     * @return $this
     */
    public function factoryState(array $state): static
    {
        return $this->state(function(array $attributes) use ($state) {
            $factoryStateKeys = $attributes['factoryState'] ?? [];

            $factoryStateKeys = array_unique(array_merge($factoryStateKeys, array_keys($state)));

            return array_merge($attributes, $state, ['factoryState' => $factoryStateKeys]);
        });
    }

    /**
     * After creating callback with factory state.
     * 
     * @param callable $callback
     * @return $this
     */
    public function afterCreatingWithFactoryState(callable $callback): static
    {
        $factoryState = null;

        return $this->afterMaking(function(Model $model) use (&$factoryState) {
            $factoryState = Arr::only($model->getAttributes(), $model->factoryState ?? []);
        })->afterCreating(function(Model $model) use (&$factoryState, $callback) {
            $callback($model, $factoryState);
        });
    }

    /**
     * Wipes the factory state before persisting to the database 
     */
    protected function clearFactoryState()
    {
        return $this->afterMaking(function(Model $model) {
            $factoryStateKeys = $model->factoryState ?? [];

            foreach ($factoryStateKeys as $key) {
                unset($model->$key);
            }

            unset($model->factoryState);
        });
    }
}