Within your WordPress plugin, you can access any data that Matomo has stored. There are two ways to do this:
When possible, it is recommended not bootstrapping Matomo for performance and stability reason. It possibly takes 50-250ms to bootstrap Matomo depending on the server and it can slow down the WordPress experience. Matomo is very powerful and therefore comes with a few dependencies. Not bootstrapping Matomo reduces the chances of WordPress breaking because some other plugin requires a dependency we require as well.
Especially in the WordPress frontend we do not recommend bootstraping Matomo but instead query the database directly when possible.
You can fetch any data by fetching data directly from the WordPress database. This is not always recommended or practical but in some cases this can be much faster and more reliable.
Example on how to fetch the list of configured goals:
$db_settings = new WpMatomo\Db\Settings();
$goal_table_name = $db_settings->prefix_table_name('goal');
global $wpdb;
$all_goals_configured_in_matomo = $wpdb->get_results('select * from ' . $goal_table_name);
Learn more about Matomo database schema View a plugin example
With just one method call you can bootstrap Matomo and afterwards access all it's HTTP API methods, PHP-APIs and Events.
Example on how to do an API call to request the list of goals and report data:
$site = new \WpMatomo\Site();
$idsite = $site->get_current_matomo_site_id();
if ($idsite) {
\WpMatomo\Bootstrap::do_bootstrap();
$all_goals_configured_in_matomo = \Piwik\API\Request::processRequest('Goals.getGoals', array(
'idSite' => $idsite
));
$country_report = \Piwik\API\Request::processRequest('UserCountry.getCountry', array(
'idSite' => $idsite,
'period' => 'day',
'date' => 'today'
));
}