Drupal Interview Questions and Answers

This page provides answers to frequently asked Drupal interview questions.

What is Drupal?

Drupal is a free, open-source content management framework written in PHP and distributed under the GNU General Public License. It's designed to easily organize, manage, and publish content, offering extensive customization features.

Commonly Used PHP-Based CMS

  • Drupal
  • Joomla
  • WordPress
  • TYPO3

Drupal's Popularity and Power

Drupal's popularity stems from its ease of use. Even users without programming skills can manage content and customize websites, making it increasingly popular.

Drupal 8 System Requirements

  • Web Server: Apache, Nginx, or Microsoft IIS
  • Database: MySQL 5.5.3/MariaDB 5.5.20/Percona Server 5.5.8 or higher (with PDO and InnoDB), PostgreSQL 9.1.2 or higher (with PDO), or SQLite 3.6.8 or higher
  • PHP: 5.5.9 or higher
  • PHP Memory: 60 MB

Drupal Features

  • Simple and secure themes
  • Mobile-first design
  • Multilingual support
  • Easy configuration and writing
  • Quick edits
  • Excellent support
  • Built-in web services
  • Fast loading speed

What is a Drupal Module?

Modules are sets of code that extend Drupal's features and functionality. There are:

  • Core modules: Included with Drupal; activated without additional software.
  • Contributed modules: Downloaded from drupal.org and installed.
  • Custom modules: Created using PHP and Drupal's module API.

Example Drupal Modules

  • Views
  • Token
  • Ctools
  • Quicktabs
  • Pathauto

What is a Drupal Sub-theme?

Sub-themes inherit from a parent theme. They offer flexibility and organization, allowing a sub-theme to be a child of another sub-theme.

What does PDO Mean?

PDO stands for PHP Data Object. It's a consistent way to access databases, enabling developers to write portable code. It's a data access layer, not an abstraction layer.

What is DRUSH?

DRUSH is a command-line shell and scripting interface for Drupal.

Can Drupal Run on the Command Line?

Yes, using DRUSH.

Why Use Ctools?

Ctools is a set of APIs and tools that improve the developer experience.

What are Render Arrays?

Render arrays are fundamental building blocks in Drupal. They provide a structured way to programmatically modify content before display.

What are Drupal Patches?

Patches are files listing differences between file sets. They're used to make additions or deletions to code, applying changes to a copy of the original file.

Disabling Core Modules

No, you cannot disable core required modules through the Drupal admin interface.

Drupal Database System

Each data type in Drupal has its own database table (e.g., node information is in the `nodes` table).

Supported Databases

Drupal supports MySQL/MariaDB, PostgreSQL, and (in Drupal 7) SQLite.

Dropping a Table with a Module

Use `db_drop_table` in the module's install file.

Drupal Distributions

Distributions are complete Drupal copies including core, modules, libraries, and installation profiles. They're useful for demonstrations, evaluations, quick site building, and learning.

Drupal Weight

Weight orders nodes. Lower weight means higher position; higher weight means lower position.

Drupal Cron

Cron is a daemon executing commands at set intervals. Drupal cron automates command or script execution.

Available Drupal Translations

Drupal supports many languages, including Catalan, Dutch, French, and Hungarian (among others).

Five Conceptual Layers in Drupal

  1. Data (nodes, etc.)
  2. Modules
  3. Blocks and menus
  4. User permissions
  5. Themes and templates

Drupal 7 API (Field API)

The Field API lets you attach custom data fields to Drupal entities, making any entity type "fieldable".

What is a Node?

In Drupal, stored content (blogs, articles, pages) are nodes. Comments are connected to nodes but aren't nodes themselves.

template.php

The `template.php` file in a theme directory lets you override theme functions.

Drupal Search vs. Other CMS

Drupal integrates well with external search engines like Xapian and Apache Solr if the built-in search isn't sufficient.

Hooks in Drupal

Hooks are Drupal API code allowing modules to interact with the core. Drupal's module system is hook-based.

Interacting with Drupal Search

Interact with Drupal's search system using:

  • nodeapi (update index)
  • hook_search()
  • hook_update_index()

Adding Custom PHP Code

Drupal doesn't allow direct PHP code insertion. Enable the "PHP filter" module to embed PHP code.

Sections Module

The Sections module lets you apply different themes to different pages on a Drupal site.

Taxonomy in Drupal

Drupal's content classification system; implemented via the core Taxonomy module.

Further reading: