PHP Classes

Simple Form Validator: Validate forms with rules defined in the HTML

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simpleformvalidator 1.0.0GNU General Publi...5HTML, PHP 5, Validation, Parsers


This class can validate forms with rules defined in the HTML.

It takes the HTML text for a form and extracts the list of inputs and validation rules that they define.

The class performs the validation of submitted values using the previously extracted rules.

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$form = new SimpleFormValidator(__DIR__.'/example.form.php');
$form->triggerCustomError('test[email][weird_name_just_to_prove_it_works]','Validation successful, custom error triggered.');
'test' =>
            array (
'email' =>
                    array (
'weird_name_just_to_prove_it_works' => '',
'repeated' => '',
'type_email' => '',
'password' => 'asdf',
'repeat_password' => 'asdf',
'a_radio_button' => 'något annat',
'foo' =>
            array (
'bar' => 'some_value',
'a_list' => 'ett konstigt värde',
'area' => 'ett konstigt värde',

?><!DOCTYPE html>
<html lang="en">
    <meta name="charset" content="UTF-8">
    <meta name="author" content="Jonas Earendel">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="description" content="PHP Form validation example.">
    <title>An example - SimpleFormValidator</title>
        display: block;
        font-weight: bold;
    .error {
        border:2px solid black;
    <h1>An example</h1>
        In this example I use GET instead of POST. This makes it easier to manipulate values and trigger errors.
        I also have words in Swedish to test unicode characters, as well as a weird variable structure.
        (The form has the <b>novalidate</b> attribute, to ensure server side validation only.)
    <form action="/example.php" method="get" novalidate>
<?php $form->html(); ?>




The purpose of SimpleFormValidator is to make user input validation secure, simple and fast.

No external rule declarations are necessary, or even possible.

SimpleFormValidator will instead extract the rules from the HTML using PHP's native DOMDocument class.

Just make sure you have valid HTML5 code, and it will work.


Three ingredients are needed to make it work:

  • The base class. (SimpleFormValidator)
  • The texts file. (So error messages can be in any language.)
  • The form body. (This can be in a file or in a string containing the form.)


The smallest example imaginable:

$form = new SimpleFormValidator('
  <input type="email" name="your_email" required>
  <input type="text" name="repeat_email" data-match="your_email">
if(!empty($_POST) && $form->validate($_POST)) {
    /do stuff; send e-mail, log in, redirect, etc./
} ?>
<form method="post" action="example.php">
    <?php $form->html(); ?>

>$_POST['your_email'] will be validated as an e-mail address. $_POST['your_email'] cannot be left empty. $_POST['repeat_email'] must match $_POST['your_email'], whether empty or not.


So, the user has entered a valid username and password, but they aren't correct.

That's when custom errors (triggerCustomError()) come in handy.

if(!empty($_POST) && $form->validate($_POST)) {
    if($user = User::fetch($_POST["username"])) {
        if($user->password == $_POST["password"]) {
            $_SESSION["user"] = $user->getAttributes();
            header("Location: welcome.php"); exit;
        } else {
            $form->triggerCustomError("password", "Password incorrect.");
    } else {
        $form->triggerCustomError("username", "User not found.");
} ?>
<form method="post" action="login.php">
    <?php $form->html(); ?>


If for instance a user is logged in and wants to send an e-mail, you can pre-populate the form. (This saves a lot of time during development.)

} ?>
<form method="post" action="contact.php">
    <?php $form->html(); ?>


The base class does not have that many validators, just the ones I've had use for lately, but that is not the end of the story.

Enter: Inheritance.

Create your own class, extending SimpleFormValidator, and add the validators you want. The existing ones can all be found in the original's constructor, if you need hints.

Like so:

class MyValidator extends SimpleFormValidator {
    function __construct($html){
        $this-> validators["number"]=function($name,$value,$node){};
        $this-> validators["zip"]=function($name,$value,$node){};
        /also add error messages to the sfv.texts_xx.php file/

I do not recommend editing SimpleFormValidator directly, since there may be updates in the future.

  Files folder image Files  
File Role Description
Plain text file class.SimpleFormValidator.php Class Class source
Accessible without login Plain text file example.form.php Aux. Auxiliary script
Accessible without login Plain text file example.php Example Example script
Accessible without login Plain text file Doc. Documentation
Accessible without login Plain text file sfv.texts_en.php Aux. Example script

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