respect-validation/docs/feature-guide.md

Feature Guide

Namespace import

Respect\Validation is namespaced, but you can make your life easier by importing a single class into your context:

use Respect\Validation\Validator as v;

Simple validation

The Hello World validator is something like this:

$number = 123;
v::numericVal()->validate($number); // true

Chained validation

It is possible to use validators in a chain. Sample below validates a string containing numbers and letters, no whitespace and length between 1 and 15.

$usernameValidator = v::alnum()->noWhitespace()->length(1, 15);
$usernameValidator->validate('alganet'); // true

Validating object attributes

Given this simple object:

$user = new stdClass;
$user->name = 'Alexandre';
$user->birthdate = '1987-07-01';

Is possible to validate its attributes in a single chain:

$userValidator = v::attribute('name', v::stringType()->length(1,32))
                  ->attribute('birthdate', v::dateTime()->age(18));

$userValidator->validate($user); // true

Validating array keys is also possible using v::key()

Note that we used v::stringType() and v::dateTime() in the beginning of the validator. Although is not mandatory, it is a good practice to use the type of the validated object as the first node in the chain.

Validating array keys and values

Validating array keys into another array is also possible using Key.

If we got the array below:

$data = [
    'parentKey' => [
        'field1' => 'value1',
        'field2' => 'value2'
        'field3' => true,
    ]
];

Using the next combination of rules, we can validate child keys.

v::key(
    'parentKey',
    v::key('field1', v::stringType())
        ->key('field2', v::stringType())
        ->key('field3', v::boolType())
    )
    ->assert($data); // You can also use check() or validate()

Input optional

On oldest versions of Respect\Validation all validators treat input as optional and accept an empty string input as valid. Even though a useful feature that caused a lot of troubles for our team and neither was an obvious behavior. Also there was some people who likes to accept null as optional value, not only an empty string.

For that reason all rules are mandatory now but if you want to treat a value as optional you can use v::optional() rule:

v::alpha()->validate(''); // false input required
v::alpha()->validate(null); // false input required

v::optional(v::alpha())->validate(''); // true
v::optional(v::alpha())->validate(null); // true

By optional we consider null or an empty string ('').

See more on Optional.

Negating rules

You can use the v::not() to negate any rule:

v::not(v::intVal())->validate(10); // false, input must not be integer

Validator reuse

Once created, you can reuse your validator anywhere. Remember $usernameValidator?

$usernameValidator->validate('respect');            //true
$usernameValidator->validate('alexandre gaigalas'); // false
$usernameValidator->validate('#$%');                //false

Exception types

• Respect\Validation\Exceptions\Exception:
  • All exceptions implement this interface;
• Respect\Validation\Exceptions\ValidationException:
  • Implements the Respect\Validation\Exceptions\Exception interface
  • Thrown when the check() fails
  • All validation exceptions extend this class
  • Available methods:
    • getMessage();
    • updateMode($mode);
    • updateTemplate($template);
• Respect\Validation\Exceptions\NestedValidationException:
  • Extends the Respect\Validation\Exceptions\ValidationException class
  • Usually thrown when the assert() fails
  • Available methods:
    • getFullMessage();
    • getMessages();

Informative exceptions

When something goes wrong, Validation can tell you exactly what's going on. For this, we use the assert() method instead of validate():

use Respect\Validation\Exceptions\NestedValidationException;

try {
    $usernameValidator->assert('really messed up screen#name');
} catch(NestedValidationException $exception) {
   echo $exception->getFullMessage();
}

The printed message is exactly this, as a nested Markdown list:

- All of the required rules must pass for "really messed up screen#name"
  - "really messed up screen#name" must contain only letters (a-z) and digits (0-9)
  - "really messed up screen#name" must not contain whitespace
  - "really messed up screen#name" must have a length between 1 and 15

Getting all messages as an array

If you want to get all the messages as an array you can use getMessages() for that. The getMessages() method returns an array with all the messages.

try {
    $usernameValidator->assert('really messed up screen#name');
} catch(NestedValidationException $exception) {
    print_r($exception->getMessages());
}

The getMessages() returns an array in which the keys are the name of the validators, or its reference in case you are using Key or Attribute rule:

Array
(
    [alnum] => "really messed up screen#name" must contain only letters (a-z) and digits (0-9)
    [noWhitespace] => "really messed up screen#name" must not contain whitespace
    [length] => "really messed up screen#name" must have a length between 1 and 15
)

Custom messages

Getting messages as an array is fine, but sometimes you need to customize them in order to present them to the user. This is possible using the getMessages() method as well by passing the templates as an argument:

try {
    $usernameValidator->assert('really messed up screen#name');
} catch(NestedValidationException $exception) {
    print_r(
        $exception->getMessages([
            'alnum' => '{{name}} must contain only letters and digits',
            'noWhitespace' => '{{name}} cannot contain spaces',
            'length' => '{{name}} must not have more than 15 chars',
        ])
    );
}

For all messages, the {{name}} variable is available for templates. If you do not define a name it uses the input to replace this placeholder.

The result of the code above will be:

Array
(
    [alnum] => "really messed up screen#name" must contain only letters and digits
    [noWhitespace] => "really messed up screen#name" cannot contain spaces
    [length] => "really messed up screen#name" must not have more than 15 chars
)

Note that getMessage() will only return a message when the specific validation in the chain fails.

Message localization

You're also able to translate your message to another language with Validation. The only thing one must do is to define the param translator as a callable that will handle the translation overwriting the default factory:

Factory::setDefaultInstance(new Factory([], [], 'gettext'));

The example above uses gettext() but you can use any other callable value, like [$translator, 'trans'] or you_custom_function().

After that, if you call getMessage(), getMessages(), or getFullMessage(), the message will be translated.

Custom rules

You can also create and use your own rules. To do this, you will need to create a rule and an exception to go with the rule.

To create a rule, you need to create a class that extends the AbstractRule class and is within the Rules namespace. When the rule is called the logic inside the validate method will be executed. Here's how the class should look:

namespace My\Validation\Rules;

use Respect\Validation\Rules\AbstractRule;

class MyRule extends AbstractRule
{
    public function validate($input): bool
    {
        // Do something here with the $input and return a boolean value
    }
}

Each rule must have an Exception to go with it. Exceptions should be named with the name of the rule followed by the word Exception. The process of creating an Exception is similar to creating a rule but there are no methods in the Exception class. Instead, you create one static property that includes an array with the information below:

namespace My\Validation\Exceptions;

use \Respect\Validation\Exceptions\ValidationException;

class MyRuleException extends ValidationException
{
    public static $defaultTemplates = [
        self::MODE_DEFAULT => [
            self::STANDARD => 'Validation message if MyRule fails validation.',
        ],
        self::MODE_NEGATIVE => [
            self::STANDARD => 'Validation message if the negative of MyRule is called and fails validation.',
        ],
    ];
}

So in the end, the folder structure for your Rules and Exceptions should look something like the structure below. Note that the folders (and namespaces) are plural but the actual Rules and Exceptions are singular.

My
 +-- Validation
     +-- Exceptions
         +-- MyRuleException.php
     +-- Rules
         +-- MyRule.php

All classes in Validation are created by the Factory class. If you want Validation to execute your rule (or rules) in the chain, you must overwrite the default Factory.

Factory::setDefaultInstance(
    new Factory(
      ['My\\Validation\\Rules'],
      ['My\\Validation\\Exceptions']
    )
);
v::myRule(); // Try to load "My\Validation\Rules\MyRule" if any
v::alnum(); // Try to use "My\Validation\Rules\Alnum" if any, or else "Respect\Validation\Rules\Alnum"

Validator name

On v::attribute() and v::key(), {{name}} is the attribute/key name. For others, is the same as the input. You can customize a validator name using:

v::dateTime('Y-m-d')->between('1980-02-02', 'now')->setName('Member Since');

Zend/Symfony validators

It is also possible to reuse validators from other frameworks if they are installed:

$hostnameValidator = v::zend('Hostname')->assert('google.com');
$timeValidator     = v::sf('Time')->assert('22:00:01');

Validation methods

We've seen validate() that returns true or false and assert() that throws a complete validation report. There is also a check() method that returns an Exception only with the first error found:

use Respect\Validation\Exceptions\ValidationException;

try {
    $usernameValidator->check('really messed up screen#name');
} catch(ValidationException $exception) {
    echo $exception->getMessage();
}

Message:

"really messed up screen#name" must contain only letters (a-z) and digits (0-9)