Reading and writing settings in Wordpress - Mini Project: Build & Apply

Reading and Writing Settings in WordPress

📖 Scenario: You are building a simple WordPress plugin that stores and retrieves a custom setting for your site. This setting controls whether a special greeting message is shown to visitors.

🎯 Goal: Build a WordPress plugin that creates a setting called show_greeting, saves its value, and reads it to decide if the greeting message should appear.

📋 What You'll Learn

Create a setting named show_greeting with a default value of false

Add a configuration variable to hold the option group name myplugin_options

Write code to update the show_greeting setting to true

Write code to read the show_greeting setting and display a greeting message if it is true

💡 Why This Matters

🌍 Real World

Many WordPress plugins need to save and read settings to customize behavior for site owners.

💼 Career

Understanding how to read and write settings is essential for WordPress plugin development and customization.

1

Create the initial setting

Create a variable called default_settings as an array with the key 'show_greeting' set to false. Then use add_option to add 'myplugin_settings' with default_settings as its value.

Wordpress

# Your code here

Hint

Use add_option('myplugin_settings', $default_settings); to create the setting with default values.

2

Add option group configuration

Create a variable called option_group and set it to the string 'myplugin_options'.

Wordpress

$default_settings = array('show_greeting' => false);
add_option('myplugin_settings', $default_settings);
# Your code here

Hint

This variable will help group your plugin's settings.

3

Update the setting value

Use get_option to get the 'myplugin_settings' array into a variable called settings. Then set settings['show_greeting'] to true. Finally, use update_option to save settings back to 'myplugin_settings'.

Wordpress

$default_settings = array('show_greeting' => false);
add_option('myplugin_settings', $default_settings);
$option_group = 'myplugin_options';
# Your code here

Hint

Use get_option and update_option to read and write settings.

4

Read the setting and display greeting

Use get_option to get 'myplugin_settings' into settings. Then use an if statement to check if settings['show_greeting'] is true. If yes, echo the string 'Hello, welcome to our site!'.

Wordpress

$default_settings = array('show_greeting' => false);
add_option('myplugin_settings', $default_settings);
$option_group = 'myplugin_options';

$settings = get_option('myplugin_settings');
$settings['show_greeting'] = true;
update_option('myplugin_settings', $settings);

# Your code here

Hint

Check the setting and show the greeting only if it is true.

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