Reading and writing settings in Wordpress - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this WordPress settings retrieval code?

Consider this code snippet that reads a setting from the WordPress options table:

 $value = get_option('my_plugin_setting', 'default');
echo $value;

Assuming the option 'my_plugin_setting' is not set in the database, what will be printed?

Wordpress

$value = get_option('my_plugin_setting', 'default');
echo $value;

A Prints 'default'

B Causes a fatal error

C Prints NULL

D Prints an empty string

💡 Hint

Check what the second parameter of get_option does.

The second parameter of get_option is the default value returned if the option does not exist. Here, it returns 'default'.

❓ state_output

intermediate

What is the value of the option after this code runs?

Given this code snippet:

 update_option('my_plugin_setting', 'blue');
update_option('my_plugin_setting', 'red');
$color = get_option('my_plugin_setting');
echo $color;

What will be the output?

Wordpress

update_option('my_plugin_setting', 'blue');
update_option('my_plugin_setting', 'red');
$color = get_option('my_plugin_setting');
echo $color;

A blue

B red

C NULL

D An error is thrown

💡 Hint

Think about what update_option does when called twice with the same key.

update_option overwrites the existing option value. The last call sets it to 'red'.

📝 Syntax

advanced

Which option causes a syntax error when saving settings?

Which of the following code snippets will cause a syntax error when trying to save a setting in WordPress?

A update_option('my_setting', array('a' => 1));

B update_option('my_setting', 'value');

C update_option('my_setting' 'value');

D update_option('my_setting', 123);

💡 Hint

Look carefully at the commas between function arguments.

Option C is missing a comma between the two arguments, causing a syntax error.

🔧 Debug

advanced

Why does this code fail to save the setting?

This code tries to save a setting but it does not persist:

 $setting = 'dark_mode';
update_option($setting, true);
if(get_option('darkmode')) {
  echo 'Enabled';
} else {
  echo 'Disabled';
}

What is the reason?

Wordpress

$setting = 'dark_mode';
update_option($setting, true);
if(get_option('darkmode')) {
  echo 'Enabled';
} else {
  echo 'Disabled';
}

A get_option requires a default value parameter

B update_option cannot save boolean values

C The variable $setting is not defined

D The option name is inconsistent between update_option and get_option

💡 Hint

Check the option names used in update_option and get_option calls.

update_option saves the value under the option name 'dark_mode' (from $setting), but get_option('darkmode') checks a different name without the underscore. Thus, get_option returns a falsey value (empty string or false), causing 'Disabled' to be printed, making it seem like the setting wasn't saved.

🧠 Conceptual

expert

Which option best describes how WordPress stores settings saved with update_option?

When you use update_option('my_setting', $value) in WordPress, how is the data stored internally?

A It stores the value serialized in the wp_options table under the option_name 'my_setting'

B It stores the value in a transient cache that expires after 1 hour

C It stores the value as plain text in a custom file in the wp-content folder

D It stores the value encrypted in the usermeta table

💡 Hint

Think about where WordPress stores options by default.

WordPress stores options in the wp_options database table. Complex data types are serialized before storage.

Practice

1. Which WordPress function is used to read a saved setting from the database?

easy

A. get_option

B. save_option

C. set_option

D. read_option

Solution

1. Step 1: Understand the purpose of each function

   get_option is the WordPress function designed to retrieve saved settings. The others are not valid WordPress functions.

2. Step 2: Confirm the correct function for reading settings

   Since get_option reads the saved option value, it is the correct choice.

3. Final Answer:

   get_option -> Option A

4. Quick Check:

   Read settings = get_option [OK]

Hint: Remember: get_option reads, update_option writes [OK]

Common Mistakes:

• Confusing get_option with update_option
• Using non-existent functions like save_option
• Thinking set_option reads settings

2. Which of the following is the correct syntax to update a setting named 'site_color' to 'blue'?

easy

A. update_option('site_color', 'blue');

B. update_option('site_color' => 'blue');

C. get_option('site_color', 'blue');

D. set_option('site_color', 'blue');

Solution

1. Step 1: Identify the correct function and syntax for updating

   The function to update a setting is update_option, which takes two parameters: the option name and the new value.

2. Step 2: Check the syntax of each option

   update_option('site_color', 'blue'); correctly uses update_option('site_color', 'blue');. update_option('site_color' => 'blue'); uses an incorrect array syntax. get_option('site_color', 'blue'); uses get_option which reads, not writes. set_option('site_color', 'blue'); uses a non-existent function.

3. Final Answer:

   update_option('site_color', 'blue'); -> Option A

4. Quick Check:

   Update syntax = update_option(name, value) [OK]

Hint: update_option needs two arguments: name and value [OK]

Common Mistakes:

• Using get_option to update values
• Passing arguments as an array instead of separate parameters
• Using non-existent set_option function

3. What will be the output of this code snippet?

$color = get_option('site_color', 'red');
echo $color;

Assuming 'site_color' is not set in the database.

medium

A. site_color

B. null

C. '' (empty string)

D. red

Solution

1. Step 1: Understand get_option default value behavior

   If the option 'site_color' does not exist, get_option returns the default value provided as the second argument, here 'red'.

2. Step 2: Determine the output of echo

   Since 'site_color' is not set, $color will be 'red', so echo outputs 'red'.

3. Final Answer:

   red -> Option D

4. Quick Check:

   Missing option returns default value [OK]

Hint: get_option returns default if option missing [OK]

Common Mistakes:

• Assuming get_option returns empty string if missing
• Confusing option name with value
• Expecting null instead of default

4. Identify the error in this code snippet:

update_option('background_color');

medium

A. Function name should be get_option to update

B. update_option cannot update 'background_color'

C. Missing the new value parameter in update_option

D. update_option requires three parameters

Solution

1. Step 1: Check update_option function parameters

   update_option requires two parameters: the option name and the new value to set.

2. Step 2: Identify the missing parameter

   The code only passes the option name, missing the new value, causing an error.

3. Final Answer:

   Missing the new value parameter in update_option -> Option C

4. Quick Check:

   update_option needs name and value [OK]

Hint: update_option always needs two arguments [OK]

Common Mistakes:

• Passing only one argument to update_option
• Confusing get_option with update_option
• Thinking update_option needs three parameters

5. You want to save a user preference 'font_size' only if it is a positive integer. Which code snippet correctly updates the setting safely?

hard

A. update_option('font_size', $_POST['font_size']);

B. $size = intval($_POST['font_size']);
if ($size > 0) {
update_option('font_size', $size);
}

C. if ($_POST['font_size']) {
update_option('font_size', $_POST['font_size']);
}

D. $size = $_POST['font_size'];
update_option('font_size', $size > 0 ? $size : 12);

Solution

1. Step 1: Validate and sanitize the input

   $size = intval($_POST['font_size']);
   if ($size > 0) {
     update_option('font_size', $size);
   }

   uses intval to convert input to integer and checks if it is positive before saving.

2. Step 2: Confirm safe update of option

   Only if the value is positive does it call update_option, preventing invalid data.

3. Final Answer:

   $size = intval($_POST['font_size']);
   if ($size > 0) {
   update_option('font_size', $size);
   } -> Option B

4. Quick Check:

   Validate input before update_option [OK]

Hint: Always validate input before update_option [OK]

Common Mistakes:

• Saving raw user input without validation
• Using update_option without checking value
• Assuming non-empty input is always valid