[change] Removed charts which have empty data #349

Closes #349

Co-authored-by: Federico Capoano <[email protected]>

openwisp_monitoring/device/api/views.py

@@ -92,6 +92,8 @@ def _get_charts_data(self, charts, time, timezone):
             # prepare chart dict
             try:
                 chart_dict = chart.read(time=time, x_axys=x_axys, timezone=timezone)
+                if not chart_dict['traces']:
+                    continue
                 chart_dict['description'] = chart.description
                 chart_dict['title'] = chart.title.format(
                     metric=chart.metric, **chart.metric.tags

openwisp_monitoring/device/tests/test_api.py

@@ -373,6 +373,17 @@ def test_histogram_csv_none_value(self):
         self.assertEqual(rows[-2].strip().split(','), ['http2', '100'])
         self.assertEqual(rows[-1].strip().split(','), ['ssh', '0'])
 
+    def test_get_device_metrics_empty(self):
+        d = self._create_device(organization=self._create_org())
+        m = self._create_object_metric(name='test_metric', content_object=d)
+        c = Chart(metric=m, configuration='dummy')  # empty chart
+        c.full_clean()
+        c.save()
+        self.assertEqual(Chart.objects.count(), 1)
+        response = self.client.get(self._url(d.pk.hex, d.key))
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.data['charts'], [])
+
     def test_get_device_metrics_400_bad_timezone(self):
         dd = self.create_test_data(no_resources=True)
         d = self.device_model.objects.get(pk=dd.pk)