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Form.php usage

Form.php is a class which contains form-related helper methods including validation.

You can download a copy of Form.php here.

Examples of Form.php in use can be found here:

Known limitations

Form.php is a rudimentary class designed to give us practice with working with external code (specifically OOP code) and form validation.

Given that, it has the following limitations:

  • Without extending the class, you can not customize the error messages, nor the name of the field they're reporting on. This is acceptable for P2.
  • There are only 11 validation rules.

I do not consider Form.php a “real world” solution— we're using it for learning/course purposes and to ease us into more sophisticated form operations and validation which we'll see when we get to Laravel.

(For some context and a preview of what's to come, you can skim the Laravel docs on validation including the over 50 different validation rules).


Place a copy of Form.php in your project.


Include Form.php and invoke the use statement to make the class avilable:

require 'Form.php';

use DWA\Form;

Instantiate an object from the Form class, passing in the $_GET or $_POST superglobal (depending on which method your form request is using):

$form = new Form($_GET);

Methods/Properties examples

The following is a series of examples showing the usage of Form's methods and properties. For complete details, read through the Form.php class.

Extract a value from the request:

$email = $form->get('email');

If the value does not exist in the request, this method will return null.

Optionally, you can provide a second parameter to use as a default if the value does not exist, e.g.:

$country = $form->get('country', 'USA');

Determine if a value is present in the request:

$email = $form->has('email');

Determine if the form submission has occurred:

$isSubmitted = $form->isSubmitted();

Access Form's hasErrors property which contains a Boolean value as to whether or not the form has errors.

$hasErrors = $form->hasErrors;

Validate form data by invoking the validate method with an array of fields => validation rules.

$errors = $form->validate(
        'email' => 'required|email',
        'url' => 'required|url',
        'username' => 'required|alphaNumeric',
        'year' => 'required|digit|minLength:4|maxLength:4',
        'total' => 'required|numeric',
        'age' => 'required|min:18',
        'score' => 'required|max:100',
        'rank' => 'required|digit|min:1|max:5',
        'rating' => 'required|numeric|min:1|max:5',

Note that a field can have multiple rules applied, with each rule separated by a | character.

The validator will loop through each field's rules, building an array of error messages. Only the first error for a given field will be reported.

Available validation rules

  • required - Value can not be blank

  • alpha - Value can only contain letters; no symbols.

  • alphaNumeric - Value can only contain letters and/or numbers; no symbols.

  • digit - The value can only contain digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

  • numeric - The value can contain only contain numbers (e.g 1, -1, 1.0)

  • email - Value must be a properly formatted email address (e.g. x@y.tld)

  • url - Value must be a properly formatted URL address

  • min:x - The value must be >= than the given parameter (x).

  • max:x - The value must be <= than the given parameter (x).

  • minLength:x - The character count of the value must be >= the given parameter (x)

  • maxLength:x - The character count of the value must be <= the given parameter (x)

(If you wish to add your own validation rules, read this: Extending Form.php)

Displaying errors

Example of how you might output the errors in your display file:

<?php if ($hasErrors) : ?>
    <div class='alert alert-danger'>
            <?php foreach ($errors as $error) : ?>
                <li><?= $error ?></li>
            <?php endforeach ?>
<?php endif ?>
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