wpMandrill $payload Filter

payload-filter.php

<?php 

# You'll need PHP 5.3+ to run this code as is. http://php.net/manual/en/functions.anonymous.php

// This action fires for an ajax event. Change it to whatever hook you need.
add_action( 'wp_ajax_todo_invite_friend', function(){

	// We're only going to apply the filter when this specific action is triggered
	add_filter( 'mandrill_payload', function( $payload ){

		$template_content = $payload['template']['content'];

		# $payload['template']['content'] # Multi-dimensional array of MC tags https://mandrill.zendesk.com/hc/en-us/articles/205582497

		$template_content = array( 
			// this corresponds to mc:edit="title"
			'name' => 'title', 
			
			// this will be the new "title" content
			'content' => "You Have Been Invited!" 
		);
		
		// Add our new template tag content to the $payload
		array_push( $payload['template']['content'], $template_content );

		return $payload;

	} );

	$email = sanitize_email( $_POST['email'] );

	$sender = get_userdata( get_current_user_id() );

	$sender = "{$sender->data->display_name} ({$sender->data->user_email})";

	// the second argument of wp_mail is passed to mc:edit="main" in our template by default
	$success = wp_mail( $email, "You've been invited!", $sender . " invited you." );

	// AJAX return values
	if ( $success ) {
		die('success');	
	} else {
		die('error');	
	}

});