ContextDefinition.php

<?php

namespace Drupal\rules\Context;

use Drupal\Core\Plugin\Context\ContextDefinition as ContextDefinitionCore;
use Drupal\Component\Plugin\Exception\ContextException;

/**
 * Extends the core context definition class with useful methods.
 *
 * This class overrides the core ContextDefinition to provide Rules-specific
 * functionality, but also to preserve the Drupal 8 behavior of
 * ContextDefinition without triggering deprecated code. Specifically, in Rules
 * we need to be able to create a ContextDefinition for ANY typed data object,
 * without prior knowledge of what that type is; we need to be able to say
 * new ContextDefinition($type) or ContextDefinition::create($type) where $type
 * may be 'integer', or 'string', or 'entity:node' etc.
 *
 * This worked in Drupal 8, but in Drupal 9 we now have to use different classes
 * for different types. Thus the core ContextDefinition::create($type) will work
 * ONLY for non-entity types, and we have to use a different way to create
 * context definitions for entities. This is a problem because now there is no
 * factory method to create context definitions, and we have to test each type
 * and just "know" the correct class to use for that type to create a context
 * definition.
 *
 * This Drupal 9 behavior is unworkable in a module like Rules where we rely on
 * introspection and reflection to manipulate typed data. Without some way to
 * programmatically create a context definition for an arbitrary data type,
 * Rules will not work.
 *
 * To work around this, we override the core ContextDefinition's __construct()
 * and create() methods. In the parent::__construct(), there is an explicit
 * assert that prevents ContextDefinition from being used for an entity. We
 * remove that here - the __construct() method of this class is otherwise
 * identical to the parent. We also override the core ContextDefinition's
 * create() method to create a Rules version of EntityContextDefinition when
 * ContextDefinition is created for an entity type. This is necessary because
 * the core EntityContextDefinition doesn't have the necessary Rules extensions
 * and there is no multiple inheritance in PHP so we have to extend
 * ContextDefinition and EntityContextDefinition separately.
 *
 * This is a poor solution that will work for existing core Rules use-cases, as
 * EntityContextDefinition is never used directly in Rules, but this may not
 * work for modules that extend Rules. A proper and permanent solution will
 * require a change to core Drupal.
 *
 * @see \Drupal\rules\Context\EntityContextDefinition
 * @see https://www.drupal.org/project/rules/issues/3161582
 * @see https://www.drupal.org/project/drupal/issues/3126747
 */
class ContextDefinition extends ContextDefinitionCore implements ContextDefinitionInterface {
    
    /**
     * {@inheritdoc}
     */
    public function __construct($data_type = 'any', $label = NULL, $required = TRUE, $multiple = FALSE, $description = NULL, $default_value = NULL) {
        $this->dataType = $data_type;
        $this->label = $label;
        $this->isRequired = $required;
        $this->isMultiple = $multiple;
        $this->description = $description;
        $this->defaultValue = $default_value;
    }
    
    /**
     * The created context definition object.
     */
    public static function create($data_type = 'any') {
        if (strpos($data_type, 'entity:') === 0) {
            return new EntityContextDefinition($data_type);
        }
        return new static($data_type);
    }
    
    /**
     * The mapping of config export keys to internal properties.
     *
     * @var array
     */
    protected static $nameMap = [
        'type' => 'dataType',
        'label' => 'label',
        'description' => 'description',
        'multiple' => 'isMultiple',
        'required' => 'isRequired',
        'default_value' => 'defaultValue',
        'constraints' => 'constraints',
        'getter' => 'getter',
        'allow_null' => 'allowNull',
        'assignment_restriction' => 'assignmentRestriction',
    ];
    
    /**
     * Name of getter function for this context variable.
     *
     * Only applicable for events.
     *
     * @var string
     */
    protected $getter = NULL;
    
    /**
     * Whether the context value is allowed to be NULL or not.
     *
     * @var bool
     */
    protected $allowNull = FALSE;
    
    /**
     * The assignment restriction of this context.
     *
     * @var string|null
     *
     * @see \Drupal\rules\Context\ContextDefinitionInterface::getAssignmentRestriction()
     */
    protected $assignmentRestriction = NULL;
    
    /**
     * {@inheritdoc}
     */
    public function toArray() {
        $values = [];
        $defaults = get_class_vars(__CLASS__);
        foreach (static::$nameMap as $key => $property_name) {
            // Only export values for non-default properties.
            if ($this->{$property_name} !== $defaults[$property_name]) {
                $values[$key] = $this->{$property_name};
            }
        }
        return $values;
    }
    
    /**
     * Creates a definition object from an exported array of values.
     *
     * @param array $values
     *   The array of values, as returned by toArray().
     *
     * @return static
     *   The created definition.
     *
     * @throws \Drupal\Component\Plugin\Exception\ContextException
     *   If the required classes are not implemented.
     */
    public static function createFromArray(array $values) {
        if (isset($values['class']) && !in_array(ContextDefinitionInterface::class, class_implements($values['class']))) {
            throw new ContextException('ContextDefinition class must implement ' . ContextDefinitionInterface::class . '.');
        }
        // Default to Rules context definition class.
        $values['class'] = $values['class'] ?? ContextDefinition::class;
        if (!isset($values['value'])) {
            $values['value'] = 'any';
        }
        $definition = $values['class']::create($values['value']);
        foreach (array_intersect_key(static::$nameMap, $values) as $key => $name) {
            $definition->{$name} = $values[$key];
        }
        return $definition;
    }
    
    /**
     * {@inheritdoc}
     */
    public function hasGetter() {
        return !is_null($this->getter);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getGetter() {
        return $this->getter;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isAllowedNull() {
        return $this->allowNull;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setAllowNull($null_allowed) {
        $this->allowNull = $null_allowed;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAssignmentRestriction() {
        return $this->assignmentRestriction;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setAssignmentRestriction($restriction) {
        $this->assignmentRestriction = $restriction;
        return $this;
    }

}