MemberPress: Display All Members Subscribed To a Specific Membership

add_shortcode( 'mepr-membership-members', function( $attributes ) {

	global $wpdb;

	// Check if a valid membership ID is provided

	if( isset( $attributes['id'] ) && is_numeric( $attributes['id'] ) ) {

          $membership_id = (int) $attributes['id'];

      } else {

	    return; // Return nothing if no valid ID is provided

	}

	// Prepare SQL query to fetch members of the specified membership

	$sql = $wpdb->prepare( "SELECT user_id FROM {$wpdb->prefix}mepr_members WHERE memberships LIKE '%d%'", $membership_id );

	$members = $wpdb->get_results( $sql, ARRAY_A );

	// Start capturing output

	ob_start();

	if ( ! empty( $members ) ) {

		echo '<ul>';

		// Loop through members and display their avatars and usernames

		foreach( $members as $member ) {

			$user = get_user_by( 'id', $member['user_id'] );

			$username = $user->user_login;

			$avatar = get_avatar_url( $member['user_id'] );

			echo '<li><img src="' . esc_url($avatar) . '"><span>' . esc_html($username) . '</span></li>';

		}

		echo '</ul>';

	}

	// Return the captured output

	return ob_get_clean();

});