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<?php

$inputFilters = [

    'cardTitle' => [
      'filter' => FILTER_CALLBACK,
      'options' => function($cardTitle) {
        return trim($cardTitle);
      }
    ],

    'cardDescription' => [
      'filter' => FILTER_CALLBACK,
      'options' => function($cardDescription) {
        return trim($cardDescription);
      }
    ],

    'districtCheckbox' => [
      'filter' => FILTER_CALLBACK,
      'flags' => FILTER_REQUIRE_ARRAY,
      'options' => function($districtCheckbox) {
        if (in_array($districtCheckbox, [1,2,3])) { // districts 1,2,3 are the possible checkbox values
          return $districtCheckbox;
        }
        return false;
      },
    ],

    'expiryDate' => [
      'filter' => FILTER_CALLBACK,
      'options' => function($expiryDate) {
        return FormInputValidator::dateFormatIsISO8601($expiryDate);
      },
    ],

  ];

  // store filtered inputs
  $inputs = filter_input_array(INPUT_POST, $inputFilters);