Setting default arguments in WordPress with wp_parse_args

The WordPress wp_parse_args function is used to merge user-defined arguments with default arguments. This can be useful for providing default values for function parameters, allowing the function to be more flexible and customizable by the user.

By using wp_parse_args, developers can easily handle and process input arguments in a consistent and predictable manner, reducing the likelihood of errors and improving the overall reliability of their code.

  • It can be particularly useful when creating WordPress plugins or themes, as it allows for easy customization and configuration by end users.
  • It also helps to maintain backward compatibility when adding new arguments to existing functions, by providing default values for any new parameters.

Parameters Accepted by the wp_parse_args Function

  • $args (string|array|object) – required. This is the value to merge with the default values.
  • $defaults (array) – optional. Default value: array(). This is an array that serves as the defaults.

Value Returned by the wp_parse_args Function

The function returns an array that contains the merged user-defined values with the defaults.


How to use wp_parse_args to merge default and user-defined arguments

Suppose you want to merge default arguments with user-defined arguments in a WordPress function. You can use wp_parse_args to achieve this:

$args = array(
 'color' => 'blue',
 'size' => 'medium',
 'shape' => 'circle'

$user_args = array(
 'size' => 'large',
 'style' => 'dotted'

$merged_args = wp_parse_args( $user_args, $args );

print_r( $merged_args );

This code snippet uses wp_parse_args to merge the $user_args array with the $args array. The resulting $merged_args array will have the values from $user_args overriding the values from $args for the keys they have in common, and include any additional keys from $user_args.

How to use wp_parse_args to set default values for function arguments

Let’s say you have a function that accepts an array of arguments, and you want to set default values for those arguments. You can use wp_parse_args to achieve this:

function custom_function( $args ) {
 $defaults = array(
 'color' => 'red',
 'size' => 'small',
 'style' => 'solid'

 $args = wp_parse_args( $args, $defaults );

 // Rest of the function code using $args

In this example, the custom_function uses wp_parse_args to merge the user-defined $args with the default $defaults. This ensures that any missing arguments in $args will be filled with the default values.

How to use wp_parse_args with URL query parameters

If you want to parse and merge URL query parameters with default arguments, you can use wp_parse_args in combination with $_GET:

$query_args = array(
 'page' => 1,
 'orderby' => 'date',
 'order' => 'asc'

$args = wp_parse_args( $_GET, $query_args );

// Use $args in your code

In this case, the wp_parse_args function is used to merge the URL query parameters from $_GET with the default $query_args. This allows you to easily handle and manipulate the query parameters in your WordPress application.


The wp_parse_args function is an essential tool for WordPress developers, allowing for efficient and reliable parsing of arguments. By providing a flexible and intuitive way to handle incoming data, it enables developers to create more robust and maintainable code. Whether used for handling user input, query parameters, or any other type of data, wp_parse_args simplifies the process of extracting and validating arguments, ultimately leading to more secure and efficient code.

In conclusion, the wp_parse_args function is a valuable asset for WordPress developers, offering a straightforward and powerful solution for parsing arguments. Its ease of use and versatility make it an indispensable tool for handling data in WordPress projects, contributing to cleaner, more reliable code. By leveraging the capabilities of wp_parse_args, developers can streamline their workflow and produce more effective and maintainable solutions.