The Drupal 8 version of EntityFieldQuery

Drupal 8's Entity Query API: A Comprehensive Guide

Drupal 8 transitioned from EntityFieldQuery (Drupal 7) to the more robust entity.query service for querying entities. This service, accessible via static calls or dependency injection, facilitates complex queries using condition methods. This guide explores its capabilities.

Key Concepts

• entity.query Service: The core of Drupal 8's entity querying. Creates query objects for specific entity types (nodes, users, etc.).
• Condition Methods: Allow filtering based on field values, class properties, and language codes (langcode).
• execute() Method: Returns an array of entity IDs.
• entity_load()/entity_load_multiple(): Functions to load single or multiple entities using their IDs.

Accessing the entity.query Service

Two methods exist for accessing the service:

1. Static Access (Less Recommended):

$query = \Drupal::entityQuery('node');

Replace 'node' with the desired entity type's machine name.

2. Dependency Injection (Recommended):

$entity_query_service = $container->get('entity.query');
$query = $entity_query_service->get('node');

This approach is preferred for better testability and decoupling.

Building Queries

Here are examples demonstrating query construction:

Simple Query (Published Nodes):

$query = \Drupal::entityQuery('node')
  ->condition('status', 1);

$nids = $query->execute();

$nids contains an array of node IDs.

Complex Query (Multiple Conditions):

$query = \Drupal::entityQuery('node')
  ->condition('status', 1)
  ->condition('changed', REQUEST_TIME, '<')
  ->condition('title', 'cat', 'CONTAINS')
  ->condition('field_tags.entity.name', 'cats');

$nids = $query->execute();

This retrieves published nodes modified before the current time, containing "cat" in the title, and referencing the "cats" taxonomy term in field_tags. Note the handling of referenced entities (field_tags.entity.name).

Condition Groups (AND/OR):

$query = \Drupal::entityQuery('node')
  ->condition('status', 1)
  ->condition('changed', REQUEST_TIME, '<');

$group = $query->orConditionGroup()
  ->condition('title', 'cat', 'CONTAINS')
  ->condition('field_tags.entity.name', 'cats');

$nids = $query->condition($group)->execute();

This uses an orConditionGroup to find nodes matching either title or tag condition. andConditionGroup is also available.

Loading Entities

After executing a query, use these functions to load entities:

Single Entity:

$node = entity_load('node', $nids[0]);

Multiple Entities:

$nodes = entity_load_multiple('node', $nids);

These functions are wrappers for the entity storage manager. Direct access via the storage manager is also possible using dependency injection:

$node_storage = $container->get('entity.manager')->getStorage('node');
$nodes = $node_storage->loadMultiple($nids);

Conclusion

Drupal 8's Entity Query API offers a significant improvement over its predecessor. Its object-oriented approach and flexible condition methods empower developers to build sophisticated entity queries. Remember to utilize dependency injection for better code practices.

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