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();

Someone make this happen.

in theory DOMDocument can help, or?

class FormFactory{

    protected $document;

    funstion __construct(){
        $this->document = new DOMDocument('1.0', 'utf-8');
    }

    function fromHtml($formHtml) {
        $this->document->loadHTML($formHtml);
    }

    function validate($data) {
        $inputs =  $this->document->getElementsByTagName('input');
        foreach($inputs as $input){
            $this->validateInput($input, $data);
        }
       ...
       ...
    }
}

@Fedik yes indeed, it can :-)

@Ocramius this is how I see a real Form library too, and why I'm against the new way of declare Form Types in Symfony :(

@mickaelandrieu while I understand where @webmozart went with that, I fully agree: the form systems are too complex and too magical, and too far from the reality of just a form to be displayed, and data to be filtered through it (moving it out of/into objects is a separate concern IMO)

there is https://github.com/joomla-framework/form not exactly what you dreams about, but close ... on some points :)
it works with "XML forms"

$formXml = <<<MYFORM
<form>
  <field type="email" name="email" label="Email:"
    required="true" rule="email" message="Enter a valid email address"/>
</form>
MYFORM;

$myForm = new Form('myform');
$myForm->load($formXml);
$myForm->validate($_POST);

but there is no asString(), all fields need to render "manually" :/

@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!)