Multiple entries in get_option results? or why is _multiwidget set to 1?

Question

I am developing a wordpress widget, and need to store some user configuration values, that is why I am using wordpress update_option and get_option. I am new to widget development.

I have some configuration options for the widget that I need to access from a php function that is called via ajax, that is why I use the Options API (is there another way?)

The code I have is the following (first, widget functions, then my ajax handling function):

public function update( $new_instance, $old_instance ) {

$instance = $old_instance;

$instance = array();
$instance['title'] = ( ! empty( $new_instance['title'] ) ) ? strip_tags( $new_instance['title'] ) : '';
$instance['api_key'] = ( ! empty ($new_instance['api_key']) ) ? strip_tags ($new_instance['api_key']) : '';
$instance['forum_key'] = ( ! empty ($new_instance['forum_key']) ) ? strip_tags ($new_instance['forum_key']) : '';
$instance['limit'] = ( ! empty ($new_instance['limit']) ) ? strip_tags ($new_instance['limit']) : '';

return $instance;

} // end widget


public function form( $instance ) {

$instance = wp_parse_args(
    (array) $instance
);

$title = ( isset ($instance['title'] ) ) ? esc_attr($instance['title']) : __( 'New title', 'eedee-dq-widget' );
$api_key = ( isset ($instance['api_key'] ) ) ? esc_attr($instance['api_key']) : '';
$forum_key = ( isset ( $instance ['forum_key'] ) ) ? esc_attr($instance['forum_key']) : '' ;
$limit = ( isset ( $instance ['limit'] ) ) ? esc_attr($instance['limit']) : 5 ;

// Display the admin form
include( plugin_dir_path(__FILE__) . '/views/admin.php' );

} // end form


public function handle_ajax_post() {

check_ajax_referer( 'my_nonce', 'security' );

if ($_SERVER['REQUEST_METHOD'] == 'POST') {

    $error = false;

    if ($error == false) {

$options = get_option('widget_my_comment_widget');
...

everything works (form values saving, ajax calling php function), the only problem is that the line

$options = get_option('widget_my_comment_widget');

returns an array like so

$options = array[3]
    $options[3] = array[4]
        $options[3]['title'] = (string) discussion
        $options[3]['api_key'] = (string) xxx
        $options[3]['forum_key'] = (string) zzz
        $options[3]['limit'] = (string) 5
    $options[4] = array[4]
        $options[4]['title'] = (string) New title
        $options[4]['api_key'] = (string) xxx
        $options[4]['forum_key'] = (string) yyy
        $options[4]['limit'] = (string) 5
    $options['_multiwidget'] = (int) 1

so it returns multiple widget configurations (why? i only have one instance of the widget in my one sidebar? because i have it in multiple themes?). How can I make sure to either get the correct id of the options I want, or make sure there is only one set of options with no id key?

Edit After disabling the plugin, removing the db entry, enabling again, adding widget again the $options look like:

$options = array[2]
    $options[2] = array[4]
        $options[2]['title'] = (string) discourse
        $options[2]['api_key'] = (string) xxx
        $options[2]['forum_key'] = (string) highcut
        $options[2]['limit'] = (string) 5
    $options['_multiwidget'] = (int) 1

so still there is this index, I googled and found it is related to the _multiwidget setting, but why is it there?

Edit 2 My constructor is

parent::__construct(
    'my_comment_widget',
    __( 'my Comment Widget', 'eedee-my-widget' ),
    array(
        'description'   =>  __( 'Displays recent and popular comments ', 'eedee-my-widget' ), )
);

so I am not using namespaces (or am I unwillingly?) like noted in this part of the official documentation, I found googling multi-widget.

Answer 1

I found the answer.

Multiwidget is a nice new feature within wordpress' new widget API. Yet there is sparse documentation on how to use it.

$options = get_option( 'your_option_id' );
if( isset($options) && isset($options[$this->number])) {
  //$this->number returns the unique widget id that corresponds to the database index
  $instance_options = $options[$this->number];
}
//now use $instance_options['setting']