APIs and Advanced Development

Question 1

Q: What is an API?

Answer 1

A: An Application Programming Interface (API) allows applications to communicate with each other by defining methods and data structures.

Question 2

Q: What is the WordPress REST API?

Answer 2

A: The WordPress REST API provides endpoints for developers to interact with WordPress sites, enabling data to be accessed and manipulated remotely.

Question 3

Q: How do you enable the WordPress REST API?

Answer 3

A: The REST API is enabled by default in WordPress; you can access it via /wp-json/ on your site.

Question 4

Q: What is an endpoint in an API?

Answer 4

A: An endpoint is a specific URL where an API interacts with data (e.g., /wp-json/wp/v2/posts for retrieving posts).

Question 5

Q: What authentication methods are commonly used with the WordPress REST API?

Answer 5

A: Basic Authentication, OAuth, Application Passwords, and JWT (JSON Web Tokens).

Question 6

Q: How does Basic Authentication work with the REST API?

Answer 6

A: It requires a username and password sent in the request header for API access.

Question 7

Q: What are Application Passwords in WordPress?

Answer 7

A: Application Passwords allow secure API authentication for individual users without sharing actual passwords.

Question 8

Q: Why should HTTPS be used when authenticating API requests?

Answer 8

A: To ensure secure transmission of credentials and protect against data interception.

Question 9

Q: What are some default endpoints provided by the WordPress REST API?

Answer 9

• /wp/v2/posts: For retrieving or managing posts.
• /wp/v2/users: For managing users.
• /wp/v2/taxonomies: For working with taxonomies.
• /wp/v2/media: For managing media uploads.

Question 10

Q: How do you fetch all posts using the REST API?

Answer 10

A: Send a GET request to /wp-json/wp/v2/posts.

Question 11

Q: How do you create a new post using the REST API?

Answer 11

A: Send a POST request to /wp-json/wp/v2/posts with the required data (e.g., title, content) and authentication.

Question 12

Q: What is the difference between GET, POST, PUT, and DELETE in API requests?

Answer 12

• GET: Retrieve data.
• POST: Create new data.
• PUT: Update existing data.
• DELETE: Remove data.

Question 13

Q: How do you create a custom REST API endpoint?

Answer 13

A: Use the register_rest_route() function in your plugin or theme.

Question 14

Q: What parameters are required in register_rest_route()?

Answer 14

A: The namespace, route, and a callback function to handle the request.

Question 15

Q: How do you add parameters to a custom REST API endpoint?

Answer 15

A: Define args in the route options, specifying parameter types and validation rules.

Question 16

Q: How do you restrict access to a custom REST API endpoint?

Answer 16

A: Use permission callback functions in register_rest_route() to check user capabilities.

Question 17

Q: What are hooks in WordPress?

Answer 17

A: Hooks are functions that allow you to modify or add functionality in WordPress without editing core files. They include actions and filters.

Question 18

Q: What is the difference between an action and a filter?

Answer 18

• Actions: Allow you to add functionality at specific points.
• Filters: Modify data before it is displayed or processed.

Question 19

Q: How do you register a custom post type?

Answer 19

A: Use the register_post_type() function in your theme or plugin.

Question 20

Q: What is a custom taxonomy, and how do you create one?

Answer 20

A: Custom taxonomies are used to organize custom post types. Use register_taxonomy() to create them.

Question 21

Q: What is AJAX in WordPress?

Answer 21

A: AJAX allows asynchronous communication between the server and client without refreshing the page.

Question 22

Q: How do you enqueue an AJAX script in WordPress?

Answer 22

A: Use wp_enqueue_script() and localize it with wp_localize_script() to pass AJAX URLs and data.

Question 23

Q: What is the role of admin-ajax.php in WordPress?

Answer 23

A: It processes AJAX requests sent from WordPress themes or plugins.

Question 24

Q: How do you create an AJAX handler in WordPress?

Answer 24

A: Add a custom action using add_action(‘wp_ajax_{action}’, ‘callback_function’) and add_action(‘wp_ajax_nopriv_{action}’, ‘callback_function’).

Question 25

Q: What is the WP REST API Schema?

Answer 25

A: It defines the structure of API data, including available endpoints, parameters, and response formats.

Question 26

Q: How can you extend existing REST API endpoints?

Answer 26

A: Use the register_rest_field() function to add custom fields or modify responses.

Question 27

Q: What is the purpose of REST API filters in WordPress?

Answer 27

A: Filters allow developers to modify requests, responses, or behavior of REST API endpoints.

Question 28

Q: How do you handle errors in the WordPress REST API?

Answer 28

A: Use the new WP_Error() class to return proper error messages with status codes.

Question 29

Q: What is GraphQL?

Answer 29

A: GraphQL is a query language for APIs that allows clients to request only the data they need.

Question 30

Q: What plugin adds GraphQL functionality to WordPress?

Answer 30

A: The “WPGraphQL” plugin.

Question 31

Q: What is the main difference between REST API and GraphQL?

Answer 31

A: REST APIs return fixed data structures, while GraphQL allows clients to define the structure of the data they need.

Question 32

Q: How do you cache REST API responses in WordPress?

Answer 32

A: Use transient APIs or external caching mechanisms like Redis.

Question 33

Q: How can you reduce the performance impact of frequent API calls?

Answer 33

A: Implement caching, batch requests, or paginate large datasets.

Question 34

Q: Why should you minimize database queries in custom API endpoints?

Answer 34

A: To improve response times and reduce server load.

Question 35

Q: What tools can you use to test REST API endpoints?

Answer 35

A: Postman, Insomnia, or the browser’s built-in fetch tool.

Question 36

Q: How do you enable debugging for API requests in WordPress?

Answer 36

A: Use the WP_DEBUG constant and log errors using error_log().

Question 37

Q: What WordPress function is used to make HTTP requests in custom API integrations?

Answer 37

A: wp_remote_get() for GET requests and wp_remote_post() for POST requests.

Question 38

Q: How do you integrate third-party APIs into WordPress?

Answer 38

A: Use HTTP request functions like wp_remote_get() or libraries like Guzzle.

Question 39

Q: What is an API key, and why is it important for third-party API integration?

Answer 39

A: An API key is a unique identifier used to authenticate API requests to third-party services.

Question 40

Q: What are webhooks, and how are they used in WordPress?

Answer 40

A: Webhooks are automated notifications sent by third-party services to a specific URL in WordPress when certain events occur.

Question 41

Q: What function is used for custom database queries in WordPress?

Answer 41

A: The $wpdb object, which allows developers to interact with the WordPress database.

Question 42

Q: How do you protect against SQL injection in custom queries?

Answer 42

A: Use prepared statements and the $wpdb->prepare() method.