Add very basic support for viewing probe readings as graph

can only view the last hour of readings, so far

tailbone/views/tempmon/probes.py

@@ -26,8 +26,11 @@ Views for tempmon probes
 
 from __future__ import unicode_literals, absolute_import
 
+import datetime
+
 import six
 
+from rattail.time import make_utc, localtime
 from rattail_tempmon.db import model as tempmon
 
 import colander
@@ -220,6 +223,46 @@ class TempmonProbeView(MasterView):
 
         g.set_sort_defaults('taken', 'desc')
 
+    def graph(self):
+        probe = self.get_instance()
+
+        # figure out which readings we need to graph
+        # TODO: make this dynamic somehow
+        cutoff = make_utc() - datetime.timedelta(seconds=3600) # last hour
+        readings = self.Session.query(tempmon.Reading)\
+                               .filter(tempmon.Reading.probe == probe)\
+                               .filter(tempmon.Reading.taken >= cutoff)\
+                               .order_by(tempmon.Reading.taken)\
+                               .all()
+
+        # convert readings to data for scatter plot
+        data = [{
+            'x': localtime(self.rattail_config, reading.taken, from_utc=True).isoformat(),
+            'y': float(reading.degrees_f),
+        } for reading in readings]
+
+        context = {
+            'probe': probe,
+            'parent_title': six.text_type(probe),
+            'parent_url': self.get_action_url('view', probe),
+            'readings_data': data,
+        }
+        return self.render_to_response('graph', context)
+
+    @classmethod
+    def defaults(cls, config):
+        route_prefix = cls.get_route_prefix()
+        url_prefix = cls.get_url_prefix()
+        model_key = cls.get_model_key()
+        permission_prefix = cls.get_permission_prefix()
+        model_title_plural = cls.get_model_title_plural()
+
+        config.add_route('{}.graph'.format(route_prefix), '{}/{{{}}}/graph'.format(url_prefix, model_key))
+        config.add_view(cls, attr='graph', route_name='{}.graph'.format(route_prefix),
+                        permission='{}.view'.format(permission_prefix))
+
+        cls._defaults(config)
+
 
 def includeme(config):
     TempmonProbeView.defaults(config)