Custom Trigger

New, custom triggers can be easily registered in your plugin or theme. All you need is a simple class declaration and a function call.

The Trigger is really only a wrapper for WordPress' action(s).

Trigger class

Have a look at the example Trigger class.

* Custom trigger class
class CustomTrigger extends \BracketSpace\Notification\Abstracts\Trigger {
* Constructor
public function __construct() {
// 1. Slug, can be prefixed with your plugin name.
// 2. Title, should be translatable.
__( 'Custom Trigger title', 'textdomain' )
// 1. Action hook.
// 2. (optional) Action priority, default: 10.
// 3. (optional) Action args, default: 1.
// It's the same as add_action( 'any_action_hook', 'callback', 10, 2 ) with
// only difference - the callback is always action() method (see below).
$this->add_action( 'any_action_hook', 10, 2 );
// 1. Trigger group, should be translatable.
// This is optional, Group is displayed in the Trigger select.
$this->set_group( __( 'My Triggers', 'textdomain' ) );
// 1. Trigger description, should be translatable.
// This is optional, Description is displayed in the Trigger select.
__( 'Fires when a page with "myparam" parameter is visited', 'textdomain' )
* Assigns action callback args to object
* Return `false` if you want to abort the trigger execution
* You can use the action method arguments as usually.
* @return mixed void or false if no notifications should be sent
public function action( $param_one, $param_two ) {
* This is a method callback hooked to the action you've added in the Constructor.
* Two important things which are happening here:
* - $this->callback_args is a numeric array containing all the callback parameters
* if you want to treat them as an array
* - if you want to abort Trigger execution, you must return false here
// If the second parameter ($process in our action) is false then abort, no carriers will be processed.
if ( false === $param_two ) {
return false;
// We can assign any property here, whole object will be accessible in Merge Tag resolver.
$this->param_value = $param_one;
* Registers attached merge tags
* @return void
public function merge_tags() {
* In this method you can assign any Merge Tags to the trigger.
* To see what Merge Tags are available go to Notification plugin's core
* and look in class/Defaults/MergeTag directory.
$this->add_merge_tag( new \BracketSpace\Notification\Defaults\MergeTag\StringTag( [
// Slug (required), this will be used as {parametrized_url} value.
// Don't translate this.
'slug' => 'parametrized_url',
// Name (required), should be translatable.
'name' => __( 'Parametrized URL', 'textdomain' ),
// Resolver (required), this can be a closure like below or function name
// like: 'parametrized_url_resolver' or array( $this, 'parametrized_url_resolver' ).
'resolver' => function( $trigger ) {
// Trigger object is available here,
// with all the properties you set in action() method.
return add_query_arg( 'source', $trigger->param_value, site_url() );
// Description (optional), should be translatable, default: ''.
'description' => __( 'Homepage URL with ?source= param', 'textdomain' ),
// Example indicator (optional)
// if true, then description will have "Example" label, default: false.
'example' => true,
] ) );

Registering the Trigger

Having this class is only a first step. To get the trigger registered you must create an instance of this class and pass it to the Notification plugin:

notification_register_trigger( new CustomTrigger() );

If you are experiencing issues like Fatal error: Class ‘BracketSpace\Notification\Abstracts\Trigger’ not found please wrap your class definition and function call in the notification/boot/initial action.