Detailed description of the wp_parse_args () function used to synthesize arrays in WordPress

This article mainly introduces the wp_parse_args () function used to synthesize arrays in WordPress, which is usually used to facilitate query. For more information, see wp_parse_args () A function is a commonly used function in the WordPress core. it is used for many purposes, but is mainly used to bind a default value to an array parameter (args.

Because the wp_parse_args () function must return an array, it will automatically convert the input query string and object into an array, giving users more convenient conditions, added compatibility.

Common query_posts (), wp_list_comments (), and get_terms () functions use the wp_parse_args () function to add default values to array parameters.

Usage

wp_parse_args( $args, $defaults );

Parameters

$ Args

(Array | string) (required) query string, object, or array parameter, used to bind the default value.

Default value: None

Query string:

type=post&posts_per_page=5&cat=1

Array:

array( 'type' => 'post', 'posts_per_page' => 5, 'cat' => '1' )

$ Defaults

(Array) (optional) default parameter of the array parameter.

Default value: Null string

Example

Function explain_parse_args ($ args = array () {// $ default value of args $ defaults = array ('before' =>'
', 'After' =>'
', 'Echo' => true, 'text' => 'WP _ parse_args () function Demo'); // bind the default value $ r = wp_parse_args ($ args, $ defaults); $ output = $ r ['before']. $ r ['text']. $ r ['after']; if (! $ R ['echo ']) return $ output; echo $ output;} // no parameter explain_parse_args (); // Print:
Wp_parse_args () function demonstration
// String parameter $ output = explain_parse_args ('text = string parameter & before =
& Echo = 0'); echo $ output; // Print:
String parameters
// Array parameter explain_parse_args (array ('text' => 'Array parameter', 'before' =>'
'); // Print:
Array parameters
Another way to avoid using the second $ ULTS parameter is to directly convert the variables of a query string, object, or array to a common array to avoid judging the type. // String $ array = wp_parse_args ('text = test another Usage & type = string'); var_dump ($ array);/* array (2) {["text"] => string (21) "test another usage" ["type"] => string (9) "string"} * // object class args_obj {public $ text = 'Test another Usage '; public $ type = 'object (object )'; function func () {// when converting to an array, the functions in the object will be ignored} $ obj = new args_obj; var_dump ($ obj);/* object (args_obj) #2175 (2) {["text"] => string (21) "test another usage" ["type"] => string (18) "object) "}*/

Wp_parse_args function Source code
The source code of the wp_parse_args function is relatively simple,
Depending on the PHP built-in functions get_object_vars, array_merge, and WordPress wp_parse_str,
The source code of the function is as follows:

/*** Merge user defined arguments into defaults array. ** This function is used throughout WordPress to allow for both string or array * to be merged into another array. ** @ since 2.2.0 ** The first parameter can be a string, array, or object (obj) * @ param string | array $ args Value to merge with $ defaults * The second parameter is the default array of values, it must be an array * @ param Array $ defaults array that serves as the defaults. * the returned value will be an array * @ return array Merged user defined values with defaults. */function wp_parse_args ($ args, $ defaults = '') {if (is_object ($ args) // the object to be received (obj) convert to array $ r = get_object_vars ($ args); elseif (is_array ($ args) // if it is an array, do not convert $ r = & $ args; else // Convert the received string to the array wp_parse_str ($ args, $ r); if (is_array ($ defaults) return array_merge ($ defaults, $ r ); return $ r ;}

The get_object_vars function is used to return an Associated array composed of object attributes.
The array_merge function combines two or more arrays. the values in an array are appended to the values of the previous array. Returns an array of results.