Add count parameter to media endpoint

docs/media.rst

@@ -185,4 +185,24 @@ Response
 
         http://api.ona.io/api/v1/media/1.jpg
 
-
+Retrieve attachment count for a form
+------------------------------------
+Returns the total number of attachments for a form
+
+.. raw:: html
+
+    <pre class="prettyprint">GET /api/v1/media/count?xform=<code>{xform_id}</code></pre>
+
+Example
+^^^^^^^
+::
+
+
+    curl -X GET https://api.ona.io/api/v1/media/count?xform=1
+
+Response
+^^^^^^^^
+::
+
+
+        {"count": 1}

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

@@ -28,6 +28,9 @@ def setUp(self):
         self.list_view = AttachmentViewSet.as_view({
             'get': 'list'
         })
+        self.count_view = AttachmentViewSet.as_view({
+            'get': 'count'
+        })
 
         self._publish_xls_form_to_project()
 
@@ -371,3 +374,11 @@ def test_direct_image_link_uppercase(self):
         self.assertEqual(response.status_code, 200)
         self.assertTrue(isinstance(response.data, basestring))
         self.assertEqual(response.data, attachment_url(self.attachment))
+
+    def test_total_count(self):
+        self._submit_transport_instance_w_attachment()
+        xform_id = self.attachment.instance.xform.id
+        request = self.factory.get(
+            '/count', data={"xform": xform_id}, **self.extra)
+        response = self.count_view(request)
+        self.assertEqual(response.data['count'], 1)

onadata/apps/api/viewsets/attachment_viewset.py

@@ -6,6 +6,7 @@
 from django.conf import settings
 from rest_framework import renderers
 from rest_framework import viewsets
+from rest_framework.decorators import action
 from rest_framework.exceptions import ParseError
 from rest_framework.response import Response
 
@@ -83,6 +84,14 @@ def retrieve(self, request, *args, **kwargs):
 
         return Response(serializer.data)
 
+    @action(methods=['GET'], detail=False)
+    def count(self, request, *args, **kwargs):
+        data = {
+            "count":  self.filter_queryset(self.get_queryset()).count()
+            }
+
+        return Response(data=data)
+
     def list(self, request, *args, **kwargs):
         if request.user.is_anonymous:
             xform = request.query_params.get('xform')