Custom Filters

A filter can be defined in two ways:

• as a callable, with the following signature:

  function (mixed $value, array $args = []): bool
  

• as class implementing Opis\JsonSchema\Filter interface. The validate method has the following signature:

  public function validate(
    Opis\JsonSchema\ValidationContext $context, 
    Opis\JsonSchema\Schema $schema, 
    array $args = []
  ): bool
  

For filters that don’t require a validation context you should use a callable - this is in 99.9% of the cases.

Using filters

You should register your filters before you validate any schema. When you register a filter you must specify:

• JSON data type (boolean, number, integer, string, null, array, object)
• name: the name you will use in your schemas
• the filter

<?php

use Opis\JsonSchema\Validator;
use Opis\JsonSchema\Resolvers\FilterResolver;

$validator = new Validator();

/** @var FilterResolver $filters */
$filters = $validator->parser()->getFilterResolver();

$modulo = function (float $value, array $args): bool {
    $divisor = $args['divisor'] ?? 1;
    $reminder = $args['reminder'] ?? 0;
    return $value % $divisor == $reminder;
};

// Register our modulo filter
$filters->registerCallable("number", "modulo", $modulo);

Here is an example of schema that uses our modulo filter

{
  "type": "number",
  "$filters": {
    "$func": "modulo",
    "$vars": {
      "divisor": 4,
      "reminder": 3
    }
  }
}

This schema validates 7 (7 % 4 == 3) but does not validate 17 (17 % 4 == 1 != 3).