New in Symfony 4.2 DivisibleBy constraint

Contributed by Colin O'Dell in #28069

In Symfony 4.2, the Validator component has introduced a new DivisibleBy constraint to check whether one number is a multiple of ("divisible by") some other number. It's mostly useful for enforcing specific increments on a number:

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// src/Entity/Item.php
namespace App\Entity;
use Symfony\Component\Validator\Constraints as Assert;

class Item
{
    /**
     * @Assert\DivisibleBy(0.25)
     */
    protected $weight;

    /**
     * @Assert\DivisibleBy(
     *     value = 5,
     *     message = "This item requires to be stocked in multiples of 5 units."
     * )
     */
    protected $quantity;
}

These constraints ensure that the weight of the Item is provided in increments of 0.25 (e.g. 0.75 and 4.50 would be correct, but 0.18 or 7.32 wouldn't) and the quantity must be divisible by 5 (25 and 22620 would be correct but 12 or 123456 wouldn't).