Drupal Development Hack: Enhancing Queries with `addTag`

By hari, 20 June, 2024

In Drupal 8 and later, addTag is a method used with entity queries to attach a tag to the query. This allows for the customisation or alteration of the query by other modules. Tags are used to identify queries and provide a mechanism to alter them using hook implementations, such as hook_query_TAG_alter.

Here's a brief overview of how you can use addTag in a query:

Basic Usage

<?php

$query = \Drupal::entityTypeManager()->getStorage('node')->getQuery();
$query->addTag('my_custom_tag');
$results = $query->execute();

In this example, the query is tagged with my_custom_tag.

Altering Queries with Tags

To alter a query tagged with my_custom_tag, you can implement hook_query_TAG_alter in a custom module. For example:

<?php

/**
 * Implements hook_query_TAG_alter() for my_custom_tag.
 */
function mymodule_query_my_custom_tag_alter(QueryAlterableInterface $query) {
  // Perform alterations to the query.
  $query->condition('status', 1);
  $query->sort('created', 'DESC');
}

In this implementation, every query tagged with my_custom_tag will have a condition added to check if the status is 1 (published nodes, for instance), and the results will be sorted by the created date in descending order.

When to Use Tags

Customization: If you need to allow other modules to alter your query, using tags is a robust way to facilitate this.
Reusability: Tags make your queries reusable and extendable by other developers or modules without directly modifying the query logic in your code.
Modularity: Tags promote modularity, ensuring that query alterations are separated from the core logic of your module.