apply_filters()
Call the functions added to a filter hook.
This function invokes all functions attached to filter hook (hook_name). It is possible to create new filter hooks by simply calling this function, specifying the name of the new hook using the (hook_name)
The function also allows for multiple additional arguments to be passed to hooks.
Example usage:
// The filter callback function. function example_callback( $string, $arg1, $arg2 ) { // (maybe) modify $string. return $string; } add_filter( 'example_filter', 'example_callback', 10, 3 );
/* * Apply the filters by calling the 'example_callback()' function * that's hooked onto `example_filter` above. * * - 'example_filter' is the filter hook. * - 'filter me' is the value being filtered. * - $arg1 and $arg2 are the additional arguments passed to the callback. $value = apply_filters( 'example_filter', 'filter me', $arg1, $arg2 );
1 time — 0.000001 sec (speed of light) | 50000 times — 0.02 sec (speed of light) | PHP 7.0.32, WP 5.0.3
No Hooks.
Return
Mixed
. The filtered value after all hooked functions are applied to it.
Usage
apply_filters( $hook_name, $value, ...$args );
- $hook_name(string) (required)
- The name of the filter hook.
- $value(mixed) (required)
- The value to filter.
- ...$args(mixed) (required)
- Additional parameters to pass to the callback functions.
Examples
#1 Usage examples
Obtaining a filtered value:
$value = apply_filters( 'filter_name', $value );
Add filter function (this code need to be executed before apply_filters() call):
add_filter( 'filter_name', 'filter_function' ); function filter_function( $value ){ return $value; }
Filter value and display it:
echo apply_filters( 'filter_name', $value );
Pass Additional Arguments for filter function:
$value = apply_filters( 'filter_name', $value, $arg1, $arg2, ... );
For example:
$value = apply_filters( 'filter_name', 'filter me', 'arg1', 'arg2 ');
Add filter function with additional arguments:
add_filter( 'filter_name', 'filter_function', 10, 3 ); function filter_function( $value, $arg1, $arg2 ){ return $value; }
#2 Example of outputting formatted content posts through a filter.
Alternative to the_content() function:
global $post; echo apply_filters( 'the_content', $post->post_content );
Notes
- Global. WP_Hook[]. $wp_filter Stores all of the filters and actions.
- Global. Int[]. $wp_filters Stores the number of times each filter was triggered.
- Global. String[]. $wp_current_filter Stores the list of current filters with the current one last.
Changelog
Since 0.71 | Introduced. |
Since 6.0.0 | Formalized the existing and already documented ...$args parameter by adding it to the function signature. |