Fundamentals of Activity-Answer Plugins

This section will help you understand how the plugin components work together within the LMS architecture. Before diving into the code, let's go over the fundamental concepts and structure.

Plugin Class Structure

Every Activity-Answer plugin consists of a PHP class that:

1. Is located in the src/Plugin/ActivityAnswer/ directory (either in your custom module, or the LMS lms_answer_plugins submodule)
    
2. Implements ActivityAnswerInterface on its own or by extending ActivityAnswerBase — this will be explained in detail later in the guide
     
3. Is given a name and ID in the ActivityAnswer attribute
    
4. Implements required methods (at minimum answeringForm())
    

The basic structure of an Activity-Answer plugin class looks like this:

<?php

declare(strict_types=1);

namespace Drupal\my_module\Plugin\ActivityAnswer;

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\lms\Attribute\ActivityAnswer;
use Drupal\lms\Entity\Answer;
use Drupal\lms\Plugin\ActivityAnswerBase;

/**
 * Provides a custom activity plugin.
 *
 * @see \Drupal\lms\Plugin\ActivityAnswerInterface
 * @see \Drupal\lms\Plugin\ActivityAnswerBase
 */
#[ActivityAnswer(
  id: 'my_custom_plugin',
  name: new TranslatableMarkup('My Custom Plugin'),
)]
final class MyCustomPlugin extends ActivityAnswerBase {

  /**
   * {@inheritdoc}
   */
  public function answeringForm(array &$form, FormStateInterface $form_state, Answer $answer): void {
    // Your form element logic goes here.
    $form['answer'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Your answer'),
      '#default_value' => $answer->getData()['answer'] ?? '',
    ];
  }

}

Activity-Answer Usage

Understanding the usage of an activity and answer is helpful for developing effective plugins. The typical lifecycle is:

1. Creation: An instructor creates an Activity, selecting an Activity Type that's associated with your plugin
    
2. Configuration: The instructor configures the Activity using the fields defined by your plugin via its config files
    
3. Presentation: A student views the activity with form elements created by your plugin’s answeringForm() method
    
4. Submission: The student submits their answer. The raw input is stored in the data field of a dedicated Answer entity
     
5. Evaluation: The answer is evaluated either:
   • Automatically by your plugin’s getScore() method, or
       
   • Manually by an instructor using your plugin’s evaluationDisplay() method
       
6. Feedback: The student receives feedback, either immediately through AJAX or after the teacher has completed their evaluation
    

Data Flow and Storage

The data flow in Activity-Answer plugins involves several entity types:

1. Activity entity (lms_activity): Stores the question and configuration
   • Custom fields defined by your plugin store instructor-configured data
       
   • These fields determine how the question is presented
       
   • Depending on the plugin, may contain: possible answers to choose from, which answer is correct, and feedback for right and wrong answers
       
2. Answer entity (lms_answer): Stores the student’s answer and evaluation results
   • data field: Contains the student’s answer as serialized data
       
   • score field: Stores the evaluated score
       
   • evaluated field: Indicates whether the answer has been evaluated