Drupal 8 — Inline validation in forms

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Article Ressources - Drupal 8 — Inline validation in forms

This is the Gist repository for my article Drupal 8 — Inline validation in forms.

Be aware that this article has been wrote for the Blog of Antistatique — Web Agency in Lausanne, Switzerland. A place where I work as Full Stack Web Developer.

Feel free to read it the full article on Medium or check it out on Antistatique.

Content of this Gist :

• ContactForm-basic.php : Basic form whitout validation
• ContactForm-validations.php : Complete form using standard Drupal 8 validations
• ContactForm-validations-inline.php : Complete form using inline validations
• InlineErrorFormTrait.php : Apply all errors as inline field error

ContactForm-basic.php

<?php
/**
* @file
* Contains \Drupal\my_contact\Form\ContactForm.
*/

namespace Drupal\my_contact\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;

// Traits
use Drupal\Core\StringTranslation\StringTranslationTrait;

class ContactForm extends FormBase {
    use StringTranslationTrait;

    /**
    * {@inheritdoc}.
    */
    public function getFormId() {
        return 'my_contact_form';
    }

    /**
    * {@inheritdoc}
    */
    public function buildForm(array $form, FormStateInterface $form_state, $params = NULL) {
        // This will generate an anchor scroll to the form when submitting
        $form['#action'] = '#my-contact-form';

        $form['personnal'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your personnal data'),
        );

        $form['personnal']['firstname'] = array(
            '#title'       => $this->t('Your firstname *'),
            '#placeholder' => $this->t('Alain'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 25],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['lastname'] = array(
            '#title'       => $this->t('Your lastname *'),
            '#placeholder' => $this->t('Rochat'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 24],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['email'] = array(
            '#title'       => $this->t('Your email *'),
            '#placeholder' => $this->t('[email protected]'),
            '#type'        => 'textfield',
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your message'),
        );

        $form['message']['subject'] = array(
            '#title'    => $this->t('Subject *'),
            '#type'     => 'textfield',
            '#required' => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message']['message'] = array(
            '#title'       => $this->t('Message *'),
            '#type'        => 'textarea',
            '#required'    => false,
            '#attributes'  => ['cols' => 59],
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['actions']['submit'] = array(
            '#type'        => 'submit',
            '#value'       => $this->t('Send'),
            '#attributes'  => ['class' => array('btn-lg btn-primary pull-right')],
            '#button_type' => 'primary',
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );
        return $form;
    }

    /**
    * {@inheritdoc}
    */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $data = array(
            'firstname' => $form_state->getValue('firstname'),
            'lastname'  => $form_state->getValue('lastname'),
            'email'     => $form_state->getValue('email'),
            'subject'   => $form_state->getValue('subject'),
            'message'   => $form_state->getValue('message'),
        );

        drupal_set_message($this->t('Thank you very much @firstname @lastname for your message. You will receive a confirmation email shortly.', [
            '@firstname' => $form_state->getValue('firstname'),
            '@lastname'  => $form_state->getValue('lastname'),
        ]));
    }
}

ContactForm-validations-full.php

<?php
/**
* @file
* Contains \Drupal\my_contact\Form\ContactForm.
*/

namespace Drupal\my_contact\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;

// Traits
use Drupal\Core\StringTranslation\StringTranslationTrait;

class ContactForm extends FormBase {
    use StringTranslationTrait;

    /**
    * {@inheritdoc}.
    */
    public function getFormId() {
        return 'my_contact_form';
    }

    /**
    * {@inheritdoc}
    */
    public function buildForm(array $form, FormStateInterface $form_state, $params = NULL) {
        // This will generate an anchor scroll to the form when submitting
        $form['#action'] = '#my-contact-form';

        $form['personnal'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your personnal data'),
        );

        $form['personnal']['firstname'] = array(
            '#title'       => $this->t('Your firstname *'),
            '#placeholder' => $this->t('Alain'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 25],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['lastname'] = array(
            '#title'       => $this->t('Your lastname *'),
            '#placeholder' => $this->t('Rochat'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 24],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['email'] = array(
            '#title'       => $this->t('Your email *'),
            '#placeholder' => $this->t('[email protected]'),
            '#type'        => 'textfield',
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your message'),
        );

        $form['message']['subject'] = array(
            '#title'    => $this->t('Subject *'),
            '#type'     => 'textfield',
            '#required' => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message']['message'] = array(
            '#title'       => $this->t('Message *'),
            '#type'        => 'textarea',
            '#required'    => false,
            '#attributes'  => ['cols' => 59],
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['actions']['submit'] = array(
            '#type'        => 'submit',
            '#value'       => $this->t('Send'),
            '#attributes'  => ['class' => array('btn-lg btn-primary pull-right')],
            '#button_type' => 'primary',
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );
        return $form;
    }

    /**
    * {@inheritdoc}
    */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        // Assert the firstname is valid
        if (!$form_state->getValue('firstname') || empty($form_state->getValue('firstname'))) {
            $form_state->setErrorByName('firstname', $this->t('Votre prénom est obligatoire.'));
        }

        // Assert the lastname is valid
        if (!$form_state->getValue('lastname') || empty($form_state->getValue('lastname'))) {
            $form_state->setErrorByName('lastname', $this->t('Votre nom est obligatoire.'));
        }

        // Assert the email is valid
        if (!$form_state->getValue('email') || !filter_var($form_state->getValue('email'), FILTER_VALIDATE_EMAIL)) {
            $form_state->setErrorByName('email', $this->t('Votre adresse e-mail semble invalide.'));
        }

        // Assert the subject is valid
        if (!$form_state->getValue('subject') || empty($form_state->getValue('subject'))) {
            $form_state->setErrorByName('subject', $this->t('Le sujet de votre demande est important.'));
        }

        // Assert the message is valid
        if (!$form_state->getValue('message') || empty($form_state->getValue('message'))) {
            $form_state->setErrorByName('message', $this->t('Le message de votre demande est important.'));
        }
    }

    /**
    * {@inheritdoc}
    */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $data = array(
            'firstname' => $form_state->getValue('firstname'),
            'lastname'  => $form_state->getValue('lastname'),
            'email'     => $form_state->getValue('email'),
            'subject'   => $form_state->getValue('subject'),
            'message'   => $form_state->getValue('message'),
        );

        drupal_set_message($this->t('Thank you very much @firstname @lastname for your message. You will receive a confirmation email shortly.', [
            '@firstname' => $form_state->getValue('firstname'),
            '@lastname'  => $form_state->getValue('lastname'),
        ]));
    }
}

ContactForm-validations-inline-full.php

<?php
/**
* @file
* Contains \Drupal\my_contact\Form\ContactForm.
*/

namespace Drupal\my_contact\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Symfony\Component\PropertyAccess\PropertyAccess;

// Traits
use Drupal\Core\StringTranslation\StringTranslationTrait;

class ContactForm extends FormBase {
    use StringTranslationTrait;

    /**
    * {@inheritdoc}.
    */
    public function getFormId() {
        return 'my_contact_form';
    }

    /**
    * {@inheritdoc}
    */
    public function buildForm(array $form, FormStateInterface $form_state, $params = NULL) {
        // This will generate an anchor scroll to the form when submitting
        $form['#action'] = '#my-contact-form';

        // Disable caching & HTML5 validation
        $form['#cache']['max-age'] = 0;
        $form['#attributes']['novalidate'] = 'novalidate';

        $form['personnal'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your personnal data'),
        );

        $form['personnal']['firstname'] = array(
            '#title'       => $this->t('Your firstname *'),
            '#placeholder' => $this->t('Alain'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 25],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['lastname'] = array(
            '#title'       => $this->t('Your lastname *'),
            '#placeholder' => $this->t('Rochat'),
            '#type'        => 'textfield',
            '#attributes'  => ['size' => 24],
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['personnal']['email'] = array(
            '#title'       => $this->t('Your email *'),
            '#placeholder' => $this->t('[email protected]'),
            '#type'        => 'textfield',
            '#required'    => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message'] = array(
          '#type'  => 'fieldset',
          '#title' => $this->t('Your message'),
        );

        $form['message']['subject'] = array(
            '#title'    => $this->t('Subject *'),
            '#type'     => 'textfield',
            '#required' => false,
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['message']['message'] = array(
            '#title'       => $this->t('Message *'),
            '#type'        => 'textarea',
            '#required'    => false,
            '#attributes'  => ['cols' => 59],
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );

        $form['actions']['submit'] = array(
            '#type'        => 'submit',
            '#value'       => $this->t('Send'),
            '#attributes'  => ['class' => array('btn-lg btn-primary pull-right')],
            '#button_type' => 'primary',
            '#prefix'      => '<div class="form-group">',
            '#suffix'      => '</div>',
        );
        return $form;
    }

    /**
    * {@inheritdoc}
    */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        // Assert the firstname is valid
        if (!$form_state->getValue('firstname') || empty($form_state->getValue('firstname'))) {
            $form_state->setErrorByName('[personnal][firstname]', $this->t('Votre prénom est obligatoire.'));
        }

        // Assert the lastname is valid
        if (!$form_state->getValue('lastname') || empty($form_state->getValue('lastname'))) {
            $form_state->setErrorByName('[personnal][lastname]', $this->t('Votre nom est obligatoire.'));
        }

        // Assert the email is valid
        if (!$form_state->getValue('email') || !filter_var($form_state->getValue('email'), FILTER_VALIDATE_EMAIL)) {
            $form_state->setErrorByName('[personnal][email]', $this->t('Votre adresse e-mail semble invalide.'));
        }

        // Assert the subject is valid
        if (!$form_state->getValue('subject') || empty($form_state->getValue('subject'))) {
            $form_state->setErrorByName('[message][subject]', $this->t('Le sujet de votre demande est important.'));
        }

        // Assert the message is valid
        if (!$form_state->getValue('message') || empty($form_state->getValue('message'))) {
            $form_state->setErrorByName('[message][message]', $this->t('Le message de votre demande est important.'));
        }

        // If validation errors, add inline errors
        if ($errors = $form_state->getErrors()) {
            // Add error to fields using Symfony Accessor
            $accessor = PropertyAccess::createPropertyAccessor();
            foreach ($errors as $field => $error) {
                if ($accessor->getValue($form, $field)) {
                    $accessor->setValue($form, $field.'[#prefix]', '<div class="form-group error">');
                    $accessor->setValue($form, $field.'[#suffix]', '<div class="input-error-desc">' .$error. '</div></div>');
                }
            }
        }
    }

    /**
    * {@inheritdoc}
    */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $data = array(
            'firstname' => $form_state->getValue('firstname'),
            'lastname'  => $form_state->getValue('lastname'),
            'email'     => $form_state->getValue('email'),
            'subject'   => $form_state->getValue('subject'),
            'message'   => $form_state->getValue('message'),
        );

        drupal_set_message($this->t('Thank you very much @firstname @lastname for your message. You will receive a confirmation email shortly.', [
            '@firstname' => $form_state->getValue('firstname'),
            '@lastname'  => $form_state->getValue('lastname'),
        ]));
    }
}

ContactForm-validations-inline.php

<?php
/**
* @file - PARTIAL 
* Contains \Drupal\my_contact\Form\ContactForm.
*/

...
    
use Symfony\Component\PropertyAccess\PropertyAccess;

...

/**
* {@inheritdoc}
*/
public function validateForm(array &$form, FormStateInterface $form_state) {
    // Assert the firstname is valid
    if (!$form_state->getValue('firstname') || empty($form_state->getValue('firstname'))) {
        $form_state->setErrorByName('[personnal][firstname]', $this->t('Votre prénom est obligatoire.'));
    }

    // Assert the lastname is valid
    if (!$form_state->getValue('lastname') || empty($form_state->getValue('lastname'))) {
        $form_state->setErrorByName('[personnal][lastname]', $this->t('Votre nom est obligatoire.'));
    }

    // Assert the email is valid
    if (!$form_state->getValue('email') || !filter_var($form_state->getValue('email'), FILTER_VALIDATE_EMAIL)) {
        $form_state->setErrorByName('[personnal][email]', $this->t('Votre adresse e-mail semble invalide.'));
    }

    // If validation errors, add inline errors
    if ($errors = $form_state->getErrors()) {
        // Add error to fields using Symfony Accessor
        $accessor = PropertyAccess::createPropertyAccessor();
        foreach ($errors as $field => $error) {
            if ($accessor->getValue($form, $field)) {
                $accessor->setValue($form, $field.'[#prefix]', '<div class="form-group error">');
                $accessor->setValue($form, $field.'[#suffix]', '<div class="input-error-desc">' .$error. '</div></div>');
            }
        }
    }
}

...

ContactForm-validations.php

<?php
/**
* @file - PARTIAL
* Contains \Drupal\my_contact\Form\ContactForm.
*/

...

/**
* {@inheritdoc}
*/
public function validateForm(array &$form, FormStateInterface $form_state) {
    // Assert the firstname is valid
    if (!$form_state->getValue('firstname') || empty($form_state->getValue('firstname'))) {
        $form_state->setErrorByName('firstname', $this->t('Votre prénom est obligatoire.'));
    }

    // Assert the lastname is valid
    if (!$form_state->getValue('lastname') || empty($form_state->getValue('lastname'))) {
        $form_state->setErrorByName('lastname', $this->t('Votre nom est obligatoire.'));
    }

    // Assert the email is valid
    if (!$form_state->getValue('email') || !filter_var($form_state->getValue('email'), FILTER_VALIDATE_EMAIL)) {
        $form_state->setErrorByName('email', $this->t('Votre adresse e-mail semble invalide.'));
    }

    // Assert the subject is valid
    if (!$form_state->getValue('subject') || empty($form_state->getValue('subject'))) {
        $form_state->setErrorByName('subject', $this->t('Le sujet de votre demande est important.'));
    }

    // Assert the message is valid
    if (!$form_state->getValue('message') || empty($form_state->getValue('message'))) {
        $form_state->setErrorByName('message', $this->t('Le message de votre demande est important.'));
    }
}

...

InlineErrorFormTrait.php

<?php

namespace Drupal\my_contact\Form;

use Symfony\Component\PropertyAccess\PropertyAccess;
use Drupal\Core\Form\FormStateInterface;

/**
 * Provides helper methods for inlining error form.
 */
trait InlineErrorFormTrait {

  /**
   * Apply all errors as inline field error.
   *
   * @param array $form
   *   The current form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   */
  public static function applyErrorsInline(array &$form, FormStateInterface $form_state) {
    // If validation errors, add inline errors.
    if ($errors = $form_state->getErrors()) {
      // Add error to fields using Symfony Accessor.
      $accessor = PropertyAccess::createPropertyAccessor();
      foreach ($errors as $field_accessor => $error) {
        try {
          $accessor->getValue($form, $field_accessor);
          if ($field = $accessor->getValue($form, $field_accessor)) {

            $prefix = str_replace('form-group', 'form-group has-danger error', $field['#prefix']);
            $suffix = '<div class="input-error-desc" id="' . $field['#id'] . '-error">' . $error . '</div>' . $field['#suffix'];

            $accessor->setValue($form, $field_accessor . '[#prefix]', $prefix);
            $accessor->setValue($form, $field_accessor . '[#suffix]', $suffix);

            $accessor->setValue($form, $field_accessor . '[#attributes][aria-invalid]', 'true');
            $accessor->setValue($form, $field_accessor . '[#attributes][aria-describedby]', $field['#id'] . '-error');
          }
        }
        catch (\Exception $e) {

        }
      }
    }
  }

}