Faker unique() causes an error

[Fukao0129]

Laravel Version

11.26.0

PHP Version

8.3.14

Database Driver & Version

8.0.36 - MySQL Community Server - GPL

Description

The seeder fails when fake()->unique() is used in a factory.

Error message:
Maximum retries of 10000 reached without finding a unique value

I'm creating 50 records:
factory()->count(50)->create()

And generating unique numbers between 1 and 50:
fake()->unique()->numberBetween(1, 50)

So unique numbers cannot be exhausted.

According to this issue, I can use fake()->unique(true).
This will eliminate errors, but it will cause data to become non-unique and duplicates to be generated.

Steps To Reproduce

1. Create a migration
2. Create a seeder

namespace Database\Seeders;

use Illuminate\Database\Seeder;
use App\Models\Example;

class ExampleTableSeeder extends Seeder
{
    public function run()
    {
        Example::factory()->count(50)->create();
    }
}

3. Create a factory

namespace Database\Factories;

use Illuminate\Database\Eloquent\Factories\Factory;

class ExampleFactory extends Factory
{
    public function definition(): array
    {
        return [
            'please_be_unique' => fake()->unique()->numberBetween(1, 50),
        ];
    }
}

4. Do migrate:fresh --seed

[timacdonald]

It is possible to generate 10,000 random numbers between 1 and 50 and not successfully generate all unique numbers from 1-50.

It could, for example, never randomly generate the number 42. Even after 10,000 attempts.

You may need to keep a static variable of values and pop them off randomly instead.

[Fukao0129]

I'm still struggling...😖

I've noticed this issue only occurs when attempting to create unique columns in multiple tables.
This issue does not occur if unique columns are created in only one table.

I've tried various things, but I haven't been able to resolve it yet.
I'd appreciate it if you could provide an update on this question.

[Fukao0129]

@timacdonald
I'm very grateful for your quick reply!
I'm sorry if there are any elementary misunderstandings about unique() method.

I'm creating 50 records:
factory()->count(50)->create()

And unique() is used for the same column in each factory.
In this case, each of the 50 values in that column will be unique.
Is it right so far?

I believe that 50 executions of fake()->unique()->numberBetween(1, 50) will create 50 records, and the numbers from 1 to 50 will each be entered into 50 records in random order.

Is this the wrong way to use it?

[rogerio-pereira]

that's expected, if you are creating 50 records, with 50 unique numbers
you need a rate of 100% acuracy, which is impossible when generating random numbers

to randomize it, you can do a for, and select a random record in your table where the column is not null, eg

for($i=1;$i<=50; $i++) {
    $model = YourModel::whereNotNull('column_with_random_number')
                ->inRandomOrder()
                ->first();
    $model->column_with_random_number = $i;
    $model->save();
}