MDL-62059 mod_book: Implement null provider for mod_book

mod/book/classes/privacy/provider.php

+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Privacy Subsystem implementation for mod_book.
+ *
+ * @package    mod_book
+ * @copyright  2018 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_book\privacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The mod_book module does not store any data.
+ *
+ * @package    mod_book
+ * @copyright  2018 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class provider implements \core_privacy\local\metadata\null_provider {
+    /**
+     * Get the language string identifier with the component's language
+     * file to explain why this plugin stores no data.
+     *
+     * @return string
+     */
+    public static function get_reason() : string {
+        return 'privacy:metadata';
+    }
+}

mod/book/lang/en/book.php

@@ -61,6 +61,7 @@ $string['indicator:socialbreadth'] = 'Book social';
 $string['indicator:socialbreadth_help'] = 'This indicator is based on the social breadth reached by the student in a Book resource.';
 $string['movechapterup'] = 'Move chapter up "{$a}"';
 $string['movechapterdown'] = 'Move chapter down "{$a}"';
+$string['privacy:metadata'] = 'The book activity module does not store any personal data.';
 $string['search:activity'] = 'Book - resource information';
 $string['search:chapter'] = 'Book - chapters';
 $string['showchapter'] = 'Show chapter "{$a}"';