Implement item update and deletion.

Deletion is essentially an update with "isDeletion" set to True.

django_etesync/migrations/0013_collectionitemrevision_is_deletion.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.3 on 2020-02-26 13:17
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etesync', '0012_auto_20200220_2038'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='collectionitemrevision',
+            name='is_deletion',
+            field=models.BooleanField(default=False),
+        ),
+    ]

django_etesync/migrations/0014_auto_20200226_1322.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.3 on 2020-02-26 13:22
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etesync', '0013_collectionitemrevision_is_deletion'),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name='collectionitemrevision',
+            old_name='is_deletion',
+            new_name='isDeletion',
+        ),
+    ]

django_etesync/migrations/0015_auto_20200226_1349.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.3 on 2020-02-26 13:49
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_etesync', '0014_auto_20200226_1322'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collectionitemrevision',
+            name='current',
+            field=models.BooleanField(blank=True, db_index=True, default=True, null=True),
+        ),
+    ]

django_etesync/models.py

@@ -80,7 +80,8 @@ class CollectionItemRevision(models.Model):
     item = models.ForeignKey(CollectionItem, related_name='revisions', on_delete=models.CASCADE)
     chunks = models.ManyToManyField(CollectionItemChunk, related_name='items')
     hmac = models.CharField(max_length=50, blank=False, null=False)
-    current = models.BooleanField(db_index=True, default=True)
+    current = models.BooleanField(db_index=True, default=True, blank=True, null=True)
+    isDeletion = models.BooleanField(default=False)
 
     class Meta:
         unique_together = ('item', 'current')

django_etesync/serializers.py

@@ -15,6 +15,7 @@
 import base64
 
 from django.contrib.auth import get_user_model
+from django.db import transaction
 from rest_framework import serializers
 from . import models
 
@@ -74,7 +75,7 @@ class CollectionItemRevisionBaseSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = models.CollectionItemRevision
-        fields = ('version', 'encryptionKey', 'chunks', 'hmac')
+        fields = ('version', 'encryptionKey', 'chunks', 'hmac', 'isDeletion')
 
 
 class CollectionItemRevisionSerializer(CollectionItemRevisionBaseSerializer):
@@ -111,12 +112,29 @@ class CollectionItemRevisionInlineSerializer(CollectionItemRevisionBaseSerialize
 
 
 class CollectionItemSerializer(serializers.ModelSerializer):
-    content = CollectionItemRevisionSerializer(read_only=True, many=False)
+    content = CollectionItemRevisionSerializer(many=False)
 
     class Meta:
         model = models.CollectionItem
         fields = ('uid', 'content')
 
+    def update(self, instance, validated_data):
+        """Function that's called when this serializer is meant to update an item"""
+        revision_data = validated_data.pop('content')
+
+        with transaction.atomic():
+            # 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 = instance.revisions.filter(current=True).select_for_update().first()
+            current_revision.current = None
+            current_revision.save()
+
+            chunks = revision_data.pop('chunks')
+            revision = models.CollectionItemRevision.objects.create(**revision_data, item=instance)
+            revision.chunks.set(chunks)
+
+        return instance
+
 
 class CollectionItemInlineSerializer(CollectionItemSerializer):
     content = CollectionItemRevisionInlineSerializer(read_only=True, many=False)

django_etesync/views.py

@@ -90,7 +90,7 @@ class CollectionViewSet(BaseViewSet):
 
 
 class CollectionItemViewSet(BaseViewSet):
-    allowed_methods = ['GET', 'POST']
+    allowed_methods = ['GET', 'POST', 'PUT']
     permission_classes = BaseViewSet.permission_classes
     queryset = CollectionItem.objects.all()
     serializer_class = CollectionItemSerializer
@@ -133,11 +133,7 @@ class CollectionItemViewSet(BaseViewSet):
         return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
     def destroy(self, request, collection_uid=None, uid=None):
-        # FIXME: implement
+        # We can't have destroy because we need to get data from the user (in the body) such as hmac.
-        return Response(status=status.HTTP_405_METHOD_NOT_ALLOWED)
-
-    def update(self, request, collection_uid=None, uid=None):
-        # FIXME: implement, or should it be implemented elsewhere?
         return Response(status=status.HTTP_405_METHOD_NOT_ALLOWED)
 
     def partial_update(self, request, collection_uid=None, uid=None):