Undefined variable trigger->post in merge tag

Hey @kubitomakita,

I am having a small issue when trying to add a merge tag to an existing trigger.

The trigger is the post published trigger that gets fired on a custom post type being published.

The trigger is working fine and the email is being sent correctly, however, I want to add in two custom field’s meta. I am getting the following error:

Notice: Undefined property: BracketSpace\Notification\Defaults\Trigger\Post\PostPublished::$post

The error is being generated when I use your example code:

// Pay attention to the Tag type you are defining.
	// If you want to output an HTML, use HtmlTag instead.
	$trigger->add_merge_tag( new BracketSpace\Notification\Defaults\MergeTag\StringTag( [
		'slug'     => 'new_merge_tag',
		'name'     => __( 'New Merge Tag', 'textdomain' ),
		'resolver' => function( $trigger ) {
			return get_post_meta( $trigger->post->ID, '_my_meta_key', true );
		},
	] ) );

I am creating the merge tags below where “memorial” is my custom post type slug.

if ( 'post/memorial/published' !== $trigger->get_slug() ) {
		return;
	}

Thanks again,

Taylor