Array Validator (regular expressions for nested array, sort of)

1.0.0 2021-02-10 06:58 UTC

This package is auto-updated.

Last update: 2023-05-29 01:07:11 UTC


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PASVL - PHP Array Structure Validation Library

Think of a regular expression [ab]+ which matches a string abab. Now imaging the same for arrays.

The purpose of this library is to validate an existing (nested) array against a template and report a mismatch. It has the object-oriented extendable architecture to write and add custom validators.

Note to current users: this version is not backwards compatible with the previous 0.5.6.


composer require lezhnev74/pasvl


Refer to files in Example folder.


Array Validation

// Define the pattern of the data, define keys and values separately
$pattern = [
    '*' => [
        'type' => 'book',
        'title' => ':string :contains("book")',
        'chapters' => [
            ':string :len(2) {1,3}' => [
                'title' => ':string',
                ':exact("interesting") ?' => ':bool',

// Provide the data to match against the above pattern.
$data = [
        'type' => 'book',
        'title' => 'Geography book',
        'chapters' => [
            'eu' => ['title' => 'Europe', 'interesting' => true],
            'as' => ['title' => 'America', 'interesting' => false],
        'type' => 'book',
        'title' => 'Foreign languages book',
        'chapters' => [
            'de' => ['title' => 'Deutsch'],

$builder = \PASVL\Validation\ValidatorBuilder::forArray($pattern);
$validator = $builder->build();
try {
} catch (ArrayFailedValidation $e) {
    // If data cannot be matched against the pattern, then exception is thrown.
    // It is not always easy to detect why the data failed matching, the exception MAY sometimes give you extra hints.
    echo "failed: " . $e->getMessage() . "\n";

Optional String Validation

$pattern = ":string :regexp('#^[ab]+$#')";
$builder = \PASVL\Validation\ValidatorBuilder::forString($pattern);
$validator = $builder->build();
$validator->validate("abab"); // the string is valid
$validator->validate("abc"); // throws RuleFailed exception with the message: "string does not match regular expression ^[ab]+$"

Validation Language

This package supports a special dialect for validation specification. It looks like this:

Short language reference:

  • Rule Name Specify zero or one Rule Name to apply to the data. Optinal postfix ? allows data to be null. Refer to the set of built-in rules in src/Validation/Rules/Library. For custom rules read below under Custom Rules. For example, :string? describes strings and null.

  • Sub-Rule Name Specify zero or more Sub-Rule Names to apply to the data AFTER the Rule is applied. Sub Rules are extra methods of the main Rule. For example, :number :float describes floats.

  • Quantifier Specify quantity expectations for data keys. If none is set then default is assumed - !. Available quantifiers:

    • ! - one key required (default)
    • ? - optional key
    • * - any count of keys
    • {2} - strict keys count
    • {2,4} - range of keys count

    For example:

      $pattern = [":string *" => ":number"];
      // the above pattern matches data:
      $data = ["june"=>10, "aug" => "11"];

Pattern Definitions

  • as exact value
    $pattern = ["name" => ":any"]; // here the key is the exact value
    $pattern = ["name?" => ":any"]; // here the key is the exact value, can be absent as well
    $pattern = [":exact('name')" => ":any"]; // this is the same
  • as nullable rule
    $pattern = ["name" => ":string?"]; // the value must be a string or null
  • as rule with subrules
    $pattern = ["name" => ":string :regexp('#\d*#')"]; // the value must be a string which contains only digits
  • as rule with quantifiers
    $pattern = [":string {2}" => ":any"]; // data must have exactly two string keys

Compound Definitions

This package supports combinations of rules, expressed in a natural language. Examples:

  • :string or :number
  • :string and :number
  • (:string and :number) or :array

There are two combination operators: and, or. and operator has precedence. Both are left-associative.

Custom Rules

By default, the system uses only the built-in rules. However you can extend them with your own implementations. To add new custom rules, follow these steps:

  • implement your new rule as a class and extend it from \PASVL\Validation\Rules\Rule
  • implement a new rule locator by extending a class \PASVL\Validation\Rules\RuleLocator
  • configure your validator like this:
    $builder = ValidatorBuilder::forArray($pattern)->withLocator(new MyLocator()); // set your new locator
    $validator = $builder->build();

Built-in Rules

This package comes with a few built-in rules and their corresponding sub-rules (see in folder src/Validation/Rules/Library):

  • :string - the value must be string
    • :regexp(<string>) - provide a regular expression(the same as for preg_match())
    • :url
    • :email
    • :uuid
    • :contains(<string>)
    • :starts(<string>)
    • :ends(<string>)
    • :in(<string>,<string>,...)
    • :len(<int>)
    • :max(<int>)
    • :min(<int>)
    • :between(<int>,<int>)
  • :number
    • :max(<int>)
    • :min(<int>)
    • :between(<int>, <int>)
    • :int - the number must be an integer
    • :float - the number must be a float
    • :positive
    • :negative
    • :in(<a>,<b>,<c>) - the number must be within values (type coercion possible)
    • :inStrict(<a>,<b>,<c>) - the number must be within values (type coercion disabled)
  • :exact(<value>)
  • :bool(<?value>) - the value must be boolean, if optional argument is given the value must be exactly it
  • :object
    • :instance(<fqcn>)
    • :propertyExists(<string>)
    • :methodExists(<string>)
  • :array
    • :count(<int>)
    • :keys(<string>,<string>,...)
    • :min(<int>) - min count
    • :max(<int>) - max count
    • :between(<int>, <int>) - count must be within
  • :any - a placeholder, any value will match


  • PHP casts "1" to 1 for array keys:
    $data = ["12" => ""];
    $pattern_invalid = [":string" => ""];
    $pattern_valid = [":number :int" => ""];
  • Technically speaking PASVL is a non-deterministic backtracking parser, and thus it can't always show you what exact key did not match the pattern. That is because, say, a key can match different patterns and there is no way of knowing which one was meant to be correct. In such cases it returns a message like "no matches found at X level".

🏆 Contributors

  • Greg Corrigan. Greg spotted a problem with nullable values reported as invalid.
  • Henry Combrinck. Henry tested the library extensively on real data and found tricky bugs and edge cases. Awesome contribution to make the package valuable to the community.
  • @Averor. Found a bug in parentheses parsing.
  • Julien Gidel. Improved regexp sub-rule.


This project is licensed under the terms of the MIT license.