Custom endpoint registration in Wordpress - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom endpoint in WordPress REST API?

A custom endpoint is a new URL path added to the WordPress REST API that allows you to create your own API routes to handle specific data or actions beyond the default WordPress endpoints.

beginner

Which WordPress function is used to register a custom REST API endpoint?

The function register_rest_route() is used to add a custom endpoint to the WordPress REST API.

intermediate

What are the main parameters of register_rest_route()?

The main parameters are:

• namespace: a string to group your routes (e.g., 'myplugin/v1')
• route: the endpoint path (e.g., '/data')
• args: an array defining HTTP methods, callback functions, permissions, and arguments

intermediate

How do you ensure only authorized users can access your custom endpoint?

You add a permission_callback function in the endpoint args that returns true if the user has permission, or false otherwise. For example, checking if the user is logged in or has a specific capability.

beginner

Where should you hook your custom endpoint registration code in WordPress?

You should hook it to the rest_api_init action. This ensures your endpoint is registered when the REST API initializes.

Which hook is used to register custom REST API endpoints in WordPress?

A wp_loaded

B init

C admin_init

D rest_api_init

The rest_api_init hook is specifically designed for registering REST API routes.

What does the register_rest_route() function NOT require?

A Namespace

B Route path

C Database connection

D Callback function

You do not need to provide a database connection when registering a REST route.

How do you restrict access to a custom endpoint to logged-in users only?

A Set <code>methods</code> to POST only

B Use <code>permission_callback</code> to check if user is logged in

C Add a nonce field in the URL

D Use <code>register_post_type</code>

The permission_callback lets you control who can access the endpoint.

What HTTP methods can you specify in register_rest_route()?

A GET, POST, PUT, DELETE, PATCH

B Only GET

C Only POST

D Only PUT and DELETE

You can specify any HTTP method supported by the REST API.

What is the purpose of the 'namespace' parameter in register_rest_route()?

A To group related endpoints under a common path

B To define the database table

C To set user permissions

D To specify the HTTP method

Namespace helps organize endpoints logically, like 'myplugin/v1'.

Explain how to create a custom REST API endpoint in WordPress from start to finish.

Think about the steps to add a new URL path that returns data securely.

Describe how permission callbacks work in custom endpoint registration and why they are important.

Consider how you keep your API safe from unwanted users.

Practice

1. What is the main purpose of using add_rewrite_endpoint in WordPress?

easy

A. To enqueue styles and scripts

B. To register a new plugin in WordPress

C. To add a new URL part (endpoint) for custom content or actions

D. To create a new database table

Solution

1. Step 1: Understand the function purpose

   add_rewrite_endpoint is used to add new URL parts to WordPress URLs.

2. Step 2: Identify correct usage context

   This function helps create custom endpoints for special content or actions, not for plugins, tables, or scripts.

3. Final Answer:

   To add a new URL part (endpoint) for custom content or actions -> Option C

4. Quick Check:

   add_rewrite_endpoint adds URL parts = D [OK]

Hint: Endpoints add URL parts for custom content [OK]

Common Mistakes:

• Confusing endpoints with plugin registration
• Thinking it creates database tables
• Assuming it loads scripts or styles

2. Which hook is the correct place to call add_rewrite_endpoint when registering a custom endpoint?

easy

A. wp_footer

B. wp_enqueue_scripts

C. admin_menu

D. init

Solution

1. Step 1: Recall WordPress hook usage

   The init hook runs early and is the recommended place to add rewrite rules and endpoints.

2. Step 2: Eliminate incorrect hooks

   wp_enqueue_scripts is for scripts/styles, admin_menu is for admin menus, and wp_footer runs late in page rendering.

3. Final Answer:

   init -> Option D

4. Quick Check:

   add_rewrite_endpoint called on init hook = A [OK]

Hint: Use init hook for rewrite endpoints [OK]

Common Mistakes:

• Using wp_enqueue_scripts instead of init
• Adding endpoints in admin_menu hook
• Placing code in wp_footer hook

3. Given this code snippet, what will be the effect on the URL structure?

add_action('init', function() {
  add_rewrite_endpoint('special', EP_PERMALINK | EP_PAGES);
});

medium

A. Adds '/special/' as an endpoint to permalinks and pages URLs

B. Removes all existing endpoints from URLs

C. Creates a new admin menu called 'special'

D. Flushes rewrite rules automatically

Solution

1. Step 1: Analyze add_rewrite_endpoint parameters

   The first parameter 'special' is the endpoint name; the second parameter sets where it applies: permalinks and pages.

2. Step 2: Understand the effect on URLs

   This adds '/special/' to URLs of posts and pages, allowing custom handling of that URL part.

3. Final Answer:

   Adds '/special/' as an endpoint to permalinks and pages URLs -> Option A

4. Quick Check:

   Endpoint 'special' added to permalinks/pages = B [OK]

Hint: Endpoint name + location = new URL part [OK]

Common Mistakes:

• Thinking it removes endpoints
• Confusing endpoints with admin menus
• Assuming rewrite rules flush automatically

4. What is missing or incorrect in this code that registers a custom endpoint?

add_action('init', function() {
  add_rewrite_endpoint('promo', EP_ROOT);
});

medium

A. The endpoint name 'promo' is invalid

B. Rewrite rules are not flushed after adding the endpoint

C. The hook 'init' is incorrect for this function

D. The constant EP_ROOT cannot be used with add_rewrite_endpoint

Solution

1. Step 1: Check endpoint registration correctness

   The endpoint name 'promo' is valid, and EP_ROOT is a valid location constant.

2. Step 2: Identify missing step

   After adding endpoints, rewrite rules must be flushed (usually once) to apply changes; this code does not flush rules.

3. Final Answer:

   Rewrite rules are not flushed after adding the endpoint -> Option B

4. Quick Check:

   Flush rewrite rules after adding endpoints = C [OK]

Hint: Flush rewrite rules after adding endpoints [OK]

Common Mistakes:

• Skipping rewrite rules flush
• Using wrong hook instead of init
• Thinking endpoint names must be special

5. You want to add a custom endpoint 'download' that works on posts and pages, and you want to flush rewrite rules only once after activation. Which code snippet correctly achieves this?

hard

A. function add_download_endpoint() {
add_rewrite_endpoint('download', EP_PERMALINK | EP_PAGES);
}
add_action('init', 'add_download_endpoint');

register_activation_hook(__FILE__, function() {
add_download_endpoint();
flush_rewrite_rules();
});

B. add_action('init', function() {
add_rewrite_endpoint('download', EP_ALL);
flush_rewrite_rules();
});

C. function add_download_endpoint() {
add_rewrite_endpoint('download', EP_ROOT);
flush_rewrite_rules();
}
add_action('init', 'add_download_endpoint');

D. register_activation_hook(__FILE__, function() {
add_rewrite_endpoint('download', EP_PERMALINK | EP_PAGES);
});

Solution

1. Step 1: Register endpoint on init hook

   Function add_download_endpoint adds the endpoint on 'init' hook, which is correct.

2. Step 2: Flush rewrite rules only once on activation

   Using register_activation_hook to call the endpoint function and then flush rewrite rules ensures flushing happens once on plugin activation.

3. Step 3: Evaluate other options

   add_action('init', function() {
     add_rewrite_endpoint('download', EP_ALL);
     flush_rewrite_rules();
   });

   flushes rules on every page load (bad).

   function add_download_endpoint() {
     add_rewrite_endpoint('download', EP_ROOT);
     flush_rewrite_rules();
   }
   add_action('init', 'add_download_endpoint');

   flushes inside init (bad).

   register_activation_hook(__FILE__, function() {
     add_rewrite_endpoint('download', EP_PERMALINK | EP_PAGES);
   });

   does not flush rules at all.

4. Final Answer:

   Register endpoint on 'init' hook and flush rewrite rules once on plugin activation -> Option A

5. Quick Check:

   Register on init + flush once on activation = A [OK]

Hint: Flush rewrite rules once on activation, not every load [OK]

Common Mistakes:

• Flushing rewrite rules on every page load
• Not flushing rewrite rules at all
• Registering endpoint outside init hook