Issue #2594553 by gambry, arshadcn, Sagar Ramgade, Yogesh Pawar, garnett2125,...

Issue #2594553 by gambry, arshadcn, Sagar Ramgade, Yogesh Pawar, garnett2125, larowlan, lauriii: Add #maxlength to textarea in Form API

core/includes/form.inc

@@ -370,12 +370,13 @@ function template_preprocess_form(&$variables) {
  * @param array $variables
  *   An associative array containing:
  *   - element: An associative array containing the properties of the element.
- *     Properties used: #title, #value, #description, #rows, #cols,
- *     #placeholder, #required, #attributes, #resizable
+ *     Properties used: #title, #value, #description, #rows, #cols, #maxlength,
+ *     #placeholder, #required, #attributes, #resizable.
  */
 function template_preprocess_textarea(&$variables) {
   $element = $variables['element'];
-  Element::setAttributes($element, ['id', 'name', 'rows', 'cols', 'placeholder']);
+  $attributes = ['id', 'name', 'rows', 'cols', 'maxlength', 'placeholder'];
+  Element::setAttributes($element, $attributes);
   RenderElement::setAttributes($element, ['form-textarea']);
   $variables['wrapper_attributes'] = new Attribute();
   $variables['attributes'] = new Attribute($element['#attributes']);

core/lib/Drupal/Core/Render/Element/Textarea.php

@@ -12,6 +12,7 @@
  * - #cols: Number of columns in the text box.
  * - #resizable: Controls whether the text area is resizable.  Allowed values
  *   are "none", "vertical", "horizontal", or "both" (defaults to "vertical").
+ * - #maxlength: The maximum amount of characters to accept as input.
  *
  * Usage example:
  * @code

core/modules/system/tests/src/Kernel/Form/FormElementMaxlengthTest.php

+<?php
+
+namespace Drupal\Tests\system\Kernel\Form;
+
+use Drupal\Core\Form\FormInterface;
+use Drupal\Core\Form\FormState;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\KernelTests\KernelTestBase;
+use Symfony\Component\CssSelector\CssSelectorConverter;
+
+/**
+ * Tests the maxlength HTML attribute on form elements.
+ *
+ * @group Form
+ */
+class FormElementMaxlengthTest extends KernelTestBase implements FormInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system'];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'form_test_maxlength';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['title'] = [
+      '#type' => 'textfield',
+      '#maxlength' => 255,
+    ];
+
+    $form['description'] = [
+      '#type' => 'textarea',
+      '#maxlength' => 255,
+    ];
+
+    $form['submit'] = [
+      '#type' => 'submit',
+      '#value' => 'Submit',
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * Ensures maxlength attribute can be used in compatible elements.
+   */
+  public function testAttributes() {
+
+    /** @var \Drupal\Core\Form\FormBuilderInterface $form_builder */
+    $form_builder = $this->container->get('form_builder');
+    $form_state = new FormState();
+    $elements = $form_builder->buildForm($this, $form_state);
+    $this->render($elements);
+
+    $css_selector_converter = new CssSelectorConverter();
+    $elements = $this->xpath($css_selector_converter->toXPath('input[name=title][maxlength=255]'));
+    $this->assertCount(1, $elements, 'Text field has correct maxlength in form.');
+    $elements = $this->xpath($css_selector_converter->toXPath('textarea[name=description][maxlength=255]'));
+    $this->assertCount(1, $elements, 'Textarea field has correct maxlength in form.');
+  }
+
+}