MDL-47322 Availability: empty availability should be saved as null

availability/classes/tree.php

@@ -575,6 +575,14 @@ public function save() {
         return $result;
     }
 
+    /**
+     * Checks whether this tree is empty (contains no children).
+     * @return boolean True if empty
+     */
+    public function is_empty() {
+        return count($this->children) === 0;
+    }
+
     /**
      * Recursively gets all children of a particular class (you can use a base
      * class to get all conditions, or a specific class).

availability/tests/tree_test.php

@@ -23,6 +23,7 @@
  */
 
 use core_availability\capability_checker;
+use \core_availability\tree;
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -488,6 +489,21 @@ public function test_get_full_information() {
                 $tree->get_full_information($info));
     }
 
+    /**
+     * Tests the is_empty() function.
+     */
+    public function test_is_empty() {
+        // Tree with nothing in should be empty.
+        $structure = self::tree(array());
+        $tree = new tree($structure);
+        $this->assertTrue($tree->is_empty());
+
+        // Tree with something in is not empty.
+        $structure = self::tree(array(self::mock(array('m' => '1'))));
+        $tree = new tree($structure);
+        $this->assertFalse($tree->is_empty());
+    }
+
     /**
      * Tests the get_all_children() function.
      */

course/modlib.php

@@ -86,6 +86,15 @@ function add_moduleinfo($moduleinfo, $course, $mform = null) {
         } else if (property_exists($moduleinfo, 'availability')) {
             $newcm->availability = $moduleinfo->availability;
         }
+        // If there is any availability data, verify it.
+        if ($newcm->availability) {
+            $tree = new \core_availability\tree(json_decode($newcm->availability));
+            // Save time and database space by setting null if the only data
+            // is an empty tree.
+            if ($tree->is_empty()) {
+                $newcm->availability = null;
+            }
+        }
     }
     if (isset($moduleinfo->showdescription)) {
         $newcm->showdescription = $moduleinfo->showdescription;
@@ -502,6 +511,15 @@ function update_moduleinfo($cm, $moduleinfo, $course, $mform = null) {
         } else if (property_exists($moduleinfo, 'availability')) {
             $cm->availability = $moduleinfo->availability;
         }
+        // If there is any availability data, verify it.
+        if ($cm->availability) {
+            $tree = new \core_availability\tree(json_decode($cm->availability));
+            // Save time and database space by setting null if the only data
+            // is an empty tree.
+            if ($tree->is_empty()) {
+                $cm->availability = null;
+            }
+        }
     }
     if (isset($moduleinfo->showdescription)) {
         $cm->showdescription = $moduleinfo->showdescription;

course/tests/courselib_test.php

@@ -460,12 +460,12 @@ private function update_specific_module_test($modulename) {
 
         // Conditional activity.
         $coursegradeitem = grade_item::fetch_course_item($moduleinfo->course); //the activity will become available only when the user reach some grade into the course itself.
-        $moduleinfo->availability = '{"op":"&","showc":[true,true],"c":[' .
+        $moduleinfo->availability = '{"op":"&","showc":[true,true,true,true,true],"c":[' .
                 '{"type":"date","d":">=","t":' . time() . '},' .
-                '{"type":"date","d":"<","t":' . (time() + (7 * 24 * 3600)) . '}' .
+                '{"type":"date","d":"<","t":' . (time() + (7 * 24 * 3600)) . '},' .
                 '{"type":"grade","id":' . $coursegradeitem->id . ',"min":10,"max":80},' .
                 '{"type":"profile","sf":"email","op":"contains","v":"@"},'.
-                '{"type":"completion","id":'. $assigncm->id . ',"e":' . COMPLETION_COMPLETE . '}' .
+                '{"type":"completion","cm":'. $assigncm->id . ',"e":' . COMPLETION_COMPLETE . '}' .
                 ']}';
 
         // Grading and Advanced grading.
@@ -2497,4 +2497,43 @@ public function test_view_resources_list() {
         $this->assertEventLegacyLogData($expectedlegacydata, $event);
         $this->assertEventContextNotUsed($event);
     }
+
+    /**
+     * Tests that when creating or updating a module, if the availability settings
+     * are present but set to an empty tree, availability is set to null in
+     * database.
+     */
+    public function test_empty_availability_settings() {
+        global $DB;
+        $this->setAdminUser();
+        $this->resetAfterTest();
+
+        // Enable availability.
+        set_config('enableavailability', 1);
+
+        // Test add.
+        $emptyavailability = '{"op":"&","c":[],"showc":[]}';
+        $course = self::getDataGenerator()->create_course();
+        $label = self::getDataGenerator()->create_module('label', array(
+                'course' => $course, 'availability' => $emptyavailability));
+        $this->assertNull($DB->get_field('course_modules', 'availability',
+                array('id' => $label->cmid)));
+
+        // Test update.
+        $formdata = $DB->get_record('course_modules', array('id' => $label->cmid));
+        unset($formdata->availability);
+        $formdata->availabilityconditionsjson = $emptyavailability;
+        $formdata->modulename = 'label';
+        $formdata->coursemodule = $label->cmid;
+        $draftid = 0;
+        file_prepare_draft_area($draftid, context_module::instance($label->cmid)->id,
+                'mod_label', 'intro', 0);
+        $formdata->introeditor = array(
+            'itemid' => $draftid,
+            'text' => '<p>Yo</p>',
+            'format' => FORMAT_HTML);
+        update_module($formdata);
+        $this->assertNull($DB->get_field('course_modules', 'availability',
+                array('id' => $label->cmid)));
+    }
 }