Add deleted_at Field to Attachments. Create soft_delete action that w…

…ill populate deleted_at field for attachments. Fixes #1696

onadata/apps/api/tests/viewsets/test_attachment_viewset.py

@@ -188,6 +188,55 @@ def test_list_view(self):
         self.assertTrue(isinstance(response.data, list))
         self.assertEqual(len(response.data), 0)
 
+    def test_list_view_surfaces_current_attachment(self):
+        self._submit_transport_instance_w_attachment()
+        filename = "1335783522564.JPG"
+        path = os.path.join(self.main_directory, 'fixtures', 'transportation',
+                            'instances', self.surveys[0], filename)
+        media_file = django_file(path, 'video2', 'image/jpeg')
+
+        Attachment.objects.create(
+            instance=self.xform.instances.first(),
+            mimetype='video/mp4',
+            extension='MP4',
+            name=filename,
+            media_file=media_file)
+
+        Attachment.objects.create(
+            instance=self.xform.instances.first(),
+            mimetype='application/pdf',
+            extension='PDF',
+            name=filename,
+            media_file=media_file)
+        Attachment.objects.create(
+            instance=self.xform.instances.first(),
+            mimetype='text/plain',
+            extension='TXT',
+            name=filename,
+            media_file=media_file)
+        Attachment.objects.create(
+            instance=self.xform.instances.first(),
+            mimetype='audio/mp3',
+            extension='MP3',
+            name=filename,
+            media_file=media_file)
+
+        request = self.factory.get('/', **self.extra)
+        response = self.list_view(request)
+        self.assertNotEqual(response.get('Cache-Control'), None)
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(isinstance(response.data, list))
+        self.assertEqual(len(response.data), 5)
+
+        # test when the attachment is soft deleted
+        self.attachment.soft_delete()
+        self.attachment.save()
+
+        request = self.factory.get('/', **self.extra)
+        response = self.list_view(request)
+
+        self.assertEqual(len(response.data), 4)
+
     def test_data_list_with_xform_in_delete_async(self):
         self._submit_transport_instance_w_attachment()
 

onadata/apps/api/viewsets/attachment_viewset.py

@@ -100,7 +100,9 @@ def list(self, request, *args, **kwargs):
                 if not xform.shared_data:
                     raise Http404(_("Not Found"))
 
-        self.object_list = self.filter_queryset(self.get_queryset())
+        request_data = self.filter_queryset(self.get_queryset())
+        self.object_list = self.object_list = [
+            a for a in request_data if a.deleted_at is None]
         page = self.paginate_queryset(self.object_list)
         if page is not None:
             serializer = self.get_serializer(page, many=True)

onadata/apps/logger/models/attachment.py

@@ -3,6 +3,7 @@
 from hashlib import md5
 
 from django.db import models
+from django.utils import timezone
 
 
 def get_original_filename(filename):
@@ -86,3 +87,14 @@ def file_hash(self):
     def filename(self):
         if self.media_file:
             return os.path.basename(self.media_file.name)
+
+    def soft_delete(self, user=None):
+        """
+        Soft deletes an attachment by adding a deleted_at timestamp.
+        """
+
+        soft_deletion_time = timezone.now()
+        self.deleted_at = soft_deletion_time
+        if user is not None:
+            self.deleted_by = user
+        self.save()

onadata/apps/logger/models/instance.py

@@ -74,6 +74,7 @@ def _get_attachments_from_instance(instance):
         attachment['mimetype'] = a.mimetype
         attachment['filename'] = a.media_file.name
         attachment['name'] = a.name
+        attachment['deleted_at'] = a.deleted_at
         attachment['instance'] = a.instance.pk
         attachment['xform'] = instance.xform.id
         attachment['id'] = a.id

onadata/libs/serializers/attachment_serializer.py

@@ -54,7 +54,7 @@ class AttachmentSerializer(serializers.HyperlinkedModelSerializer):
     class Meta:
         fields = ('url', 'filename', 'mimetype', 'field_xpath', 'id', 'xform',
                   'instance', 'download_url', 'small_download_url',
-                  'medium_download_url')
+                  'medium_download_url', 'deleted_at')
         model = Attachment
 
     @check_obj