Drupal Drupal Module Development & API 2

Question 1

Which Drupal hook allows a module to alter an existing form before it is rendered?

Accepted Answer

hook_form_alter()

Answer

hook_form_alter() receives the form array by reference and lets any module modify fields, validators, submit handlers, or structure of any form.

Question 2

In Drupal, what is the purpose of the #cache property in a render array?

Accepted Answer

Define cache tags, contexts, and max-age for granular caching

Answer

The #cache property with tags, contexts, and max-age keys lets Drupal cache render array output at the right granularity and invalidate it precisely.

Question 3

What Drupal API is used to execute a database query that loads multiple nodes matching specific field values?

Accepted Answer

EntityQuery via \Drupal::entityQuery()

Answer

EntityQuery (via \Drupal::entityQuery() or injected entity type manager) provides a safe, entity-aware query builder that respects access control.

Question 4

What is a Drupal 'Event Subscriber' and which Symfony component does it leverage?

Accepted Answer

A class that listens to dispatched events using Symfony EventDispatcher

Answer

Event Subscribers implement EventSubscriberInterface from Symfony's EventDispatcher component and react to events like KernelEvents::REQUEST without using hooks.

Question 5

In Drupal's Plugin API, what is the role of the @annotation on a plugin class?

Accepted Answer

Registers the plugin with Drupal's plugin manager at discovery time

Answer

Drupal uses Doctrine annotations (like @Block, @Field, @ViewsField) in class docblocks to auto-discover and register plugins without manual registry files.

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Drupal Drupal Module Development & API 2