Enable emptying of documentation fields

Previously empty strings where not properly handled and the previous
value persisted.

aleksis/apps/alsijil/frontend/components/coursebook/documentation/LessonSummary.vue

@@ -92,9 +92,9 @@ export default {
   emits: ["open"],
   data() {
     return {
-      topic: "",
-      homework: "",
-      groupNote: "",
+      topic: null,
+      homework: null,
+      groupNote: null,
     };
   },
   methods: {
@@ -113,10 +113,10 @@ export default {
       };
     },
     save() {
-      if (this.topic || this.homework || this.groupNote) {
-        const topic = this.topic ? { topic: this.topic } : {};
-        const homework = this.homework ? { homework: this.homework } : {};
-        const groupNote = this.groupNote ? { groupNote: this.groupNote } : {};
+      if (this.topic !== null || this.homework !== null || this.groupNote !== null) {
+        const topic = this.topic !== null ? { topic: this.topic } : {};
+        const homework = this.homework !== null ? { homework: this.homework } : {};
+        const groupNote = this.groupNote !== null ? { groupNote: this.groupNote } : {};
 
         this.createOrPatch([
           {
@@ -127,9 +127,9 @@ export default {
           },
         ]);
 
-        this.topic = "";
-        this.homework = "";
-        this.groupNote = "";
+        this.topic = null;
+        this.homework = null;
+        this.groupNote = null;
       }
     },
     saveAndBlur(event) {

aleksis/apps/alsijil/schema/documentation.py

@@ -175,11 +175,11 @@ class DocumentationBatchCreateOrUpdateMutation(graphene.Mutation):
             if not info.context.user.has_perm("alsijil.edit_documentation_rule", obj):
                 raise PermissionDenied()
 
-            if doc.topic:
+            if doc.topic is not None:
                 obj.topic = doc.topic
-            if doc.homework:
+            if doc.homework is not None:
                 obj.homework = doc.homework
-            if doc.group_note:
+            if doc.group_note is not None:
                 obj.group_note = doc.group_note
 
             obj.save()