Collection remove the redundant mainItem model attr.

django_etesync/migrations/0039_remove_collection_mainitem.py

@@ -0,0 +1,17 @@
+# Generated by Django 3.0.3 on 2020-04-16 08:28
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etesync', '0038_remove_collectionitemrevision_chunks'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='collection',
+            name='mainItem',
+        ),
+    ]

django_etesync/models.py

@@ -29,7 +29,6 @@ class Collection(models.Model):
                            max_length=44, validators=[UidValidator])
     version = models.PositiveSmallIntegerField()
     owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
-    mainItem = models.OneToOneField('CollectionItem', related_name='of_collection', null=True, on_delete=models.SET_NULL)
 
     class Meta:
         unique_together = ('uid', 'owner')
@@ -37,9 +36,13 @@ class Collection(models.Model):
     def __str__(self):
         return self.uid
 
+    @cached_property
+    def main_item(self):
+        return self.items.get(uid=None)
+
     @cached_property
     def content(self):
-        return self.mainItem.content
+        return self.main_item.content
 
 
 class CollectionItem(models.Model):

django_etesync/serializers.py

@@ -185,11 +185,9 @@ class CollectionSerializer(serializers.ModelSerializer):
             instance.save()
             main_item = models.CollectionItem.objects.create(
                 uid=None, encryptionKey=None, version=instance.version, collection=instance)
-            instance.mainItem = main_item
 
             process_revisions_for_item(main_item, revision_data)
 
-            instance.save()
             models.CollectionMember(collection=instance,
                                     user=validated_data.get('owner'),
                                     accessLevel=models.CollectionMember.AccessLevels.ADMIN,
@@ -203,7 +201,7 @@ class CollectionSerializer(serializers.ModelSerializer):
         revision_data = validated_data.pop('content')
 
         with transaction.atomic():
-            main_item = instance.mainItem
+            main_item = instance.main_item
             # We don't have to use select_for_update here because the unique constraint on current guards against
             # the race condition. But it's a good idea because it'll lock and wait rather than fail.
             current_revision = main_item.revisions.filter(current=True).select_for_update().first()