Form validation from HTML form

html-form-validator-factory.php

<?php

$formHtml = <<<'HTML'
<form action="%s" method="post">
    <label for="email">Email:</label>
    <input
        type="email"
        id="email"
        name="email"
        value=""
        aria-describedby="email-description"
        data-reuse-submitted-value="true"
        data-validator="email-address"
        required="required"
    />
    <span id="email-description" class="help">Enter a valid email address</span>
    <input type="submit"/>
</form>
HTML;

$form = $formFactory->fromHtml($formHtml);

var_dump($form->validate($_POST)); // returns form validion result VO

echo $form->asString();

@Fedik that is kinda useless: what I want to get rid of is a DSL for forms that is NOT an HTML form. The HTML forms specification includes loads of stuff that already covers most use-cases of forms, therefore we should just stop re-implementing it from scratch.

@Ocramius nice idea. Probably I would use 3 different validation methods: validateFromGlobals() ($_POST or $_GET depending on form method) validateArray() and validateRequest() for PSR-7 request object.

Also, you probably need to know when form is submitted and when not.

/** @var FormLib\FormtInterface $validation */
$form = $formFactory->fromHtml($formHtml);
/** @var FormLib\ValidationObjectInterface $validation */
$validation = $form->validateFromGlobals();
/** @var string[] $messages */
$messages = $form->isSubmitted() ? $validation->getErrorMessages() : [];
/** @var array $data */
$data = $form->data(); // strips any information in globals that is not provided by form, empty when form not submitted

if ($messages) {
   vprintf(
     '<ul class="form-errors">'.str_repeat('<li>%s</li>', count($messages)).'</ul>',
     array_map('htmlentities', $messages)
   );
} elseif(!$form->isSubmitted()) {
  echo $form; // __toString()
}

if ($data) {
   $success = do_something_with_data($data);
   echo $success ? '<p>Thank You!</p>' : '<p>Something bad happened.</p>';
}

Regarding implementation, using https://github.com/Level-2/Transphporm should be quite simple.

Those are controller concerns imo, not form's.

How about this: https://github.com/xtreamwayz/html-form-validator

@xtreamwayz that kinda resembles my thoughts. I forgot to mention that @jstoone already started work on this at jstoone/HTMLFormValidator#1

Opened https://github.com/xtreamwayz/html-form-validator/issues/1 to avoid you folks stumbling on each other by accident (do it on purpose!)