30+ Drupal Developer Interview Questions and Answers

Composer is a dependency manager for PHP. Drupal can be updated through composer using the command line.

• Composer is used to manage dependencies in PHP projects

• To update Drupal using composer, run the command 'composer update drupal/core --with-dependencies'

• Composer.lock file should be committed to version control

Position Absolute is positioned relative to its closest positioned ancestor, while Position Relative is positioned relative to its normal position.

• Position Absolute removes the element from the normal flow of the document, while Position Relative does not.

• Position Absolute is often used for overlaying elements on top of each other, while Position Relative is used for minor positioning adjustments.

• Position Absolute coordinates are calculated based on the nearest positioned anc...read more

Multiple databases can be connected to Drupal using the Database API and configuring settings.php file.

• Use the Database API to connect to additional databases

• Add the database connection details to settings.php file

• Use the db_set_active() function to switch between databases

• Use the db_query() function to execute queries on the selected database

Custom modules and themes can be created in Drupal using PHP and CSS/HTML respectively.

• To create a custom module, define a .info.yml file, a .module file, and a .routing.yml file.

• To create a custom theme, define a .info.yml file, a .theme file, and a .libraries.yml file.

• Use Drupal's hook system to add functionality to your module.

• Use Twig templates to customize the HTML/CSS of your theme.

• Use Drupal's theming functions to add dynamic content to your theme.

• Examples of custom mo...read more

To export a database, you can use tools like phpMyAdmin or command line.

• Use phpMyAdmin to export database by selecting the database, clicking on 'Export', and choosing the desired format.

• Use command line to export database using commands like mysqldump.

• You can also use Drupal modules like Backup and Migrate to export database.

• Make sure to choose the correct format and settings for the export.

MySQL types of Joins, Delete vs TRUNCATE

• Types of Joins in MySQL: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN

• DELETE statement removes specific rows from a table based on a condition

• TRUNCATE statement removes all rows from a table without logging individual row deletions

To enable twig debug, set debug to true in the twig configuration file.

• Edit the development.services.yml file in the sites/default folder

• Set debug to true under the twig.config section

• Clear the cache to apply changes

An abstract class is a class that cannot be instantiated and is used as a base for other classes to inherit from.

• Cannot be instantiated on its own

• May contain abstract methods that must be implemented by child classes

• Can have both abstract and non-abstract methods

Drupal views allow for filtering and aggregating content based on context filters.

• Context filters allow you to filter content based on contextual information, such as the current user or page being viewed.

• Aggregation allows you to group and summarize content based on certain criteria, such as counting the number of items in a category.

• Combining context filters and aggregation can provide powerful ways to display and analyze content in Drupal views.

Caching is the process of storing frequently accessed data in a temporary storage to improve performance.

• Caching reduces the number of requests made to the server, thus improving website speed.

• Drupal has built-in caching mechanisms such as page caching, block caching, and dynamic caching.

• Caching can be configured and customized based on specific needs and requirements.

• Examples of caching tools include Memcached, Redis, and Varnish.

Print and echo are both used to output data in PHP, but echo is slightly faster and can output multiple values at once.

• Print is a language construct while echo is a language construct and a function.

• Echo can output multiple values at once while print can only output one value at a time.

• Echo is slightly faster than print because it does not return a value.

Views are a powerful Drupal module that allows users to create custom queries and display data in various formats.

• Views allow users to create custom queries without writing any code

• Users can display data in various formats such as tables, grids, lists, etc.

• Views can be used to create complex filters and sorts for data

• Views can be used to create custom pages, blocks, and feeds

• Views can be extended with custom code and plugins

T function is used in Drupal to translate text strings into the current language of the website.

• T function is used to translate text strings in Drupal.

• It is used to ensure that text displayed on the website is in the correct language.

• Developers can use the T function in their code to make it multilingual.

• Example: t('Hello world') will translate 'Hello world' into the current language of the website.

Drupal is a popular open-source content management system used to create and manage websites.

• Drupal is known for its flexibility and scalability, making it suitable for a wide range of websites from personal blogs to large corporate sites.

• It offers a wide range of modules and themes that can be used to customize the appearance and functionality of a website.

• Drupal has a strong community of developers and users who contribute to its ongoing development and support.

• It is built ...read more

Version control system is a tool that helps track changes to files and manage different versions of code.

• Allows multiple developers to work on the same codebase

• Tracks changes made to files over time

• Helps in reverting to previous versions if needed

• Examples: Git, SVN, Mercurial

To debug errors in production environment, follow these steps

• Check error logs for specific error messages

• Use debugging tools like Xdebug or Drupal's built-in debugging features

• Review recent code changes that may have caused the error

• Test the code on a local environment to replicate the issue

• Consult with team members or online forums for assistance

Event subscriber example in Drupal development

• Event subscribers allow modules to subscribe to and respond to events triggered by the Drupal core or other modules

• Event subscribers are defined in a module's services.yml file

• Example: Creating an event subscriber to log user login events

Types of Drupal entities include nodes, users, taxonomy terms, and custom entities.

• Nodes: Basic content type in Drupal, can represent articles, pages, etc.

• Users: Represents individuals who can log in and interact with the site.

• Taxonomy terms: Used for categorizing content.

• Custom entities: Entities created by developers for specific needs.

Git commands include add, commit, push, pull, merge, branch, checkout, and clone.

• git add - stages changes for commit

• git commit - records changes to the repository

• git push - uploads local changes to a remote repository

• git pull - downloads changes from a remote repository

• git merge - combines changes from different branches

• git branch - lists, creates, or deletes branches

• git checkout - switches branches or restores files

• git clone - creates a copy of a repository

Different types of joins in SQL help combine data from multiple tables based on a related column between them.

• INNER JOIN: Returns rows when there is at least one match in both tables.

• LEFT JOIN: Returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN: Returns all rows from the right table and the matched rows from the left table.

• FULL JOIN: Returns rows when there is a match in one of the tables.

• CROSS JOIN: Returns the Cartesian product of the ...read more

Cache mechanism in Drupal helps improve performance by storing data temporarily.

• Drupal uses caching to store data temporarily to reduce load times.

• Cache can be configured in Drupal admin settings.

• Examples of cache mechanisms in Drupal include page cache, block cache, and views cache.

The top valuation in the task refers to the highest possible value or rating that can be achieved.

• Identify the criteria for evaluation and determine the maximum possible score or rating.

• Ensure that all aspects of the task are thoroughly assessed to reach the top valuation.

• Consider any bonus points or extra credit that may contribute to achieving the highest valuation.

Creating a custom theme in Drupal involves creating a new folder in the themes directory and adding necessary files.

• Create a new folder in the themes directory with a unique name

• Add a .info.yml file to define the theme

• Create a .theme file for theme-specific functions

• Add CSS and JS files for styling and functionality

• Enable the custom theme in the Drupal admin interface

Custom form methods in Drupal allow developers to create and manipulate forms in unique ways.

• Custom form methods can be used to alter form elements, validate form submissions, and process form data.

• Examples include using hook_form_alter to modify existing forms, implementing custom form validation functions, and creating custom submit handlers.

• Custom form methods can also be used to create entirely new forms from scratch.

• These methods provide flexibility and customization opt...read more

A Drupal developer is a professional who specializes in developing websites and applications using the Drupal content management system.

• Specializes in developing websites and applications using Drupal CMS

• Creates custom modules and themes

• Works with PHP, HTML, CSS, and JavaScript

• Collaborates with designers and content creators

• Troubleshoots and maintains Drupal websites

Drush is a command line tool for managing Drupal websites, while Composer is a dependency manager for PHP.

• Drush is used for performing common tasks like clearing caches, updating modules, and running database updates.

• Composer is used for managing dependencies in PHP projects by defining them in a 'composer.json' file.

• Drush and Composer are often used together in Drupal projects to manage dependencies and perform tasks efficiently.

Headless Drupal is a content management system where the front-end and back-end are decoupled, allowing for more flexibility and customization.

• Headless Drupal separates the content management system (back-end) from the presentation layer (front-end).

• It allows developers to use any front-end technology, such as React or Angular, to build the user interface.

• APIs are used to connect the front-end to the back-end, enabling content to be delivered to various devices and platforms....read more

Multilingual in Drupal refers to the ability of the CMS to support multiple languages on a single website.

• Drupal core provides multilingual capabilities out of the box

• Content can be translated into different languages using the built-in translation interface

• Language detection and selection can be configured for users

• Modules like Internationalization (i18n) can enhance multilingual functionality

Five commonly used array functions in PHP

• array_push() - adds one or more elements to the end of an array

• array_pop() - removes and returns the last element of an array

• array_merge() - merges one or more arrays into a single array

• array_filter() - filters elements of an array using a callback function

• array_slice() - extracts a slice of an array

Taxonomy is a way to classify and organize content in a structured manner.

• Taxonomy helps categorize content into different groups or categories.

• It allows for easier navigation and filtering of content on a website.

• In Drupal, taxonomy terms can be used to tag content and create relationships between different pieces of content.

To create a custom block in Drupal, you can use the Block module or create a custom module with a block plugin.

• Enable the Block module if not already enabled

• Navigate to Structure > Block layout to add a new custom block

• Or create a custom module with a block plugin to define the block's content and settings

Views is a powerful Drupal module that allows users to create custom queries and displays of content.

• Views allows users to create custom queries of content on a Drupal site.

• Users can customize the display of content using various formatting options.

• Views can be used to create lists, tables, grids, and other displays of content.

• Views can also be used to create custom reports and data visualizations.

• Views is a versatile tool that can be used to create dynamic and interactive di...read more

Types of loops in PHP include for, while, do-while, and foreach loops.

• For loop: Executes a block of code a specified number of times.

• While loop: Executes a block of code as long as a specified condition is true.

• Do-while loop: Executes a block of code once, then repeats the loop as long as a specified condition is true.

• Foreach loop: Used to iterate over arrays or objects.

Variables in Twig are used to store and display dynamic content in Drupal templates.

• Variables in Twig are enclosed in double curly braces {{ }}.

• Variables can be assigned values in the template or passed from the controller.

• Variables can be used to output content, perform calculations, or control the flow of the template.

• Example: {{ variable_name }}

• Example: {% if variable_name %} do something {% endif %}