Form State

It is impossible to mention Drupal Web Development without bringing up the topic of Form State. How your form maintains its ‘state’ or information during user interaction plays a crucial role in the usability and functionality of your website. The Form State is an array that stores temporary form data including the form’s build ID, form object, and user input.

Here’s what that looks like in code:

$form_state = [
  'build_info' => [
    'form_id' => $form_id,
  ],
  'values' => [],
];

In the form state, $form_id is a unique string that identifies the form, allowing Drupal to validate and rebuild it when necessary. The $form_state['values'] array collects and stores user input from the form.

Form State is not just a passive data storage system; it’s also instrumental in guiding the form through different stages of its lifecycle. In Drupal, forms have several defined stages - building, validation, submission, and redirecting. For instance, during the form validation stage, Drupal uses the data stored in the form state to confirm the integrity of user input.

function my_module_form_submit($form, &$form_state) {
  if ($form_state['values']['input'] <= 0) {
    form_set_error('input', t('Input must be a positive number.'));
  }
}

In this validation example, data from the Form State is used to check if the user’s input is a positive number. If not, Drupal uses form_set_error() to inform the user of their incorrect input.

However, Form State also represents a considerable risk if not managed correctly. Because it preserves data entered by users, it could potentially contain sensitive details. It is essential, thus, to avoid storing unnecessary confidential information such as passwords in the form state.

Implementing a secure Drupal website isn’t solely about sanitizing user input or proper session management. It also involves correctly managing form states. By using form states effectively, developers can ensure their website is not just user-friendly, but also adheres to best practices in keeping user data protected.

Finally, to maintain the website’s performance, remember that form states, as in other Drupal cache data, should be cleared periodically, especially when they contain a lot of data or are no longer needed.

$form_state = form_state_defaults();
cache_clear_all('form:'. $form_build_id, 'cache_form');

In conclusion, mastering Form State manipulation is crucial in Drupal Development. This powerful feature allows developers to store and retrieve form data during multiple stages and user interactions. However, be careful to manage Form State responsibly to ensure your Drupal website remains secure against potential threats.