Common action hooks in Wordpress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a function to the WordPress 'init' action hook.

Wordpress

add_action('init', [1]);

Drag options to blanks, or click blank then click option'

A'admin_menu'

B'wp_head'

C'the_content'

D'my_init_function'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a hook name instead of a function name.

Not putting the function name in quotes.

The 'init' hook runs after WordPress has finished loading but before any headers are sent. You add your function name as a string to it.

2fill in blank

medium

Complete the code to hook a function to run when the WordPress admin menu is being built.

Wordpress

add_action('admin_menu', [1]);

Drag options to blanks, or click blank then click option'

A'my_admin_menu_function'

B'template_redirect_function'

C'init_function'

D'wp_footer_function'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function name unrelated to admin menu.

Confusing hook names with function names.

The 'admin_menu' hook is used to add items to the WordPress admin menu. You provide your function name as a string.

3fill in blank

hard

Fix the error in the code to correctly hook a function to the 'wp_footer' action.

Wordpress

add_action('wp_footer', [1]);

Drag options to blanks, or click blank then click option'

AmyFooterFunction()

Bmy_footer_function

C'my_footer_function'

D'myFooterFunction()'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the function name without quotes.

Including parentheses when passing the function name.

The function name must be passed as a string without parentheses to 'add_action'.

4fill in blank

hard

Fill both blanks to add a function with priority 15 and 2 accepted arguments to the 'save_post' action hook.

Wordpress

add_action('save_post', [1], [2], 2);

Drag options to blanks, or click blank then click option'

A'my_save_post_function'

B10

C15

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong priority number.

Not passing the function name as a string.

You pass the function name as a string, then the priority number (15 here), and finally the number of arguments (2).

5fill in blank

hard

Fill all three blanks to add a function to the 'template_redirect' hook with priority 20 and accepting 1 argument.

Wordpress

add_action([1], [2], [3], 1);

Drag options to blanks, or click blank then click option'

A'template_redirect'

B'my_template_redirect_function'

C20

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up hook and function names.

Using wrong priority number.

Not passing strings for names.

The first argument is the hook name as a string, second is the function name as a string, third is the priority number (20 here), and fourth is the number of accepted arguments (1).

Practice

1. Which WordPress action hook is commonly used to run code after WordPress has finished loading but before any headers are sent?

easy

A. wp_footer

B. wp_head

C. save_post

D. init

Solution

1. Step 1: Understand the purpose of init hook

   The init hook runs after WordPress loads but before headers are sent, ideal for initialization tasks.

2. Step 2: Compare with other hooks

   wp_head and wp_footer run during page rendering, save_post runs on post save, so they don't fit the timing.

3. Final Answer:

   init -> Option D

4. Quick Check:

   Initialization hook = init [OK]

Hint: Remember: init runs early after loading [OK]

Common Mistakes:

• Confusing wp_head with init
• Thinking save_post runs on page load
• Mixing wp_footer timing with init

2. Which of the following is the correct syntax to add a function named my_custom_function to the wp_footer action hook?

easy

A. add_action('wp_footer', my_custom_function);

B. add_action(wp_footer, 'my_custom_function');

C. add_action('wp_footer', 'my_custom_function');

D. add_action('wp_footer', my_custom_function());

Solution

1. Step 1: Check the function name parameter

   The function name must be passed as a string, so quotes are required around 'my_custom_function'.

2. Step 2: Verify the hook name and function call

   The hook name must be a string, so 'wp_footer' is correct. The function should not be called (no parentheses).

3. Final Answer:

   add_action('wp_footer', 'my_custom_function'); -> Option C

4. Quick Check:

   Function name as string, no parentheses [OK]

Hint: Function names in add_action must be quoted strings [OK]

Common Mistakes:

• Passing function name without quotes
• Calling the function with parentheses inside add_action
• Not quoting the hook name string

3. What will be the output when the following code runs in a WordPress theme?

add_action('wp_head', function() { echo '<!-- Header comment -->'; });

medium

A. The code will cause a fatal error due to incorrect hook usage.

B. The comment <!-- Header comment --> will appear inside the HTML <head> section.

C. The comment will not appear because anonymous functions are not allowed.

D. The comment will appear at the bottom of the page before </body>.

Solution

1. Step 1: Understand the wp_head hook timing

   The wp_head hook runs inside the HTML <head> section of the page.

2. Step 2: Analyze the anonymous function output

   The function echoes an HTML comment, so it will be output exactly where the hook runs, inside <head>.

3. Final Answer:

   The comment <!-- Header comment --> will appear inside the HTML <head> section. -> Option B

4. Quick Check:

   wp_head outputs inside <head> [OK]

Hint: Remember wp_head outputs inside <head> tag [OK]

Common Mistakes:

• Thinking output appears in footer
• Believing anonymous functions are disallowed
• Assuming hook causes error

4. Identify the error in this code snippet that tries to save custom data when a post is saved:

add_action('save_post', 'save_custom_data');
function save_custom_data() {
  update_post_meta(get_the_ID(), 'custom_key', 'custom_value');
}

medium

A. The function save_custom_data should accept the post ID parameter.

B. The hook name should be 'save_post_data' instead of 'save_post'.

C. update_post_meta cannot be used inside save_post hook.

D. get_the_ID() returns the wrong post ID inside save_post.

Solution

1. Step 1: Check the save_post hook function signature

   The save_post hook passes the post ID as a parameter to the callback function, so the function must accept it.

2. Step 2: Analyze the function usage of get_the_ID()

   get_the_ID() may not return the correct post ID in this context; the passed post ID parameter should be used instead.

3. Final Answer:

   The function save_custom_data should accept the post ID parameter. -> Option A

4. Quick Check:

   save_post callback needs post ID parameter [OK]

Hint: save_post callback must accept post ID parameter [OK]

Common Mistakes:

• Ignoring the post ID parameter in callback
• Using wrong hook name
• Assuming get_the_ID() works inside save_post

5. You want to add a custom script only on the front page footer using WordPress hooks. Which combination of hooks and conditions is the best approach?

hard

A. Use add_action('wp_footer', 'my_script_function') and inside the function check is_front_page() before outputting the script.

B. Use add_action('init', 'my_script_function') and output the script directly.

C. Use add_action('wp_head', 'my_script_function') without any condition.

D. Use add_action('save_post', 'my_script_function') to add the script on front page.

Solution

1. Step 1: Identify the correct hook for footer scripts

   The wp_footer hook is the proper place to add scripts before the closing </body> tag.

2. Step 2: Use conditional check for front page

   Inside the callback, use is_front_page() to ensure the script runs only on the front page.

3. Final Answer:

   Use add_action('wp_footer', 'my_script_function') and inside the function check is_front_page() before outputting the script. -> Option A

4. Quick Check:

   Footer hook + front page check = Use add_action('wp_footer', 'my_script_function') and inside the function check is_front_page() before outputting the script. [OK]

Hint: Add scripts in wp_footer with is_front_page() check [OK]

Common Mistakes:

• Using init hook to output scripts directly
• Adding scripts in wp_head without condition
• Using save_post hook for front page scripts