This ensures that we post the latest non null data

Not just the latest data.

We should handle no data better than having to find that {} has no key
for our data point.

backdrop/transformers/tasks/latest_transaction_explorer_values.py

@@ -29,9 +29,12 @@
     config.STAGECRAFT_OAUTH_TOKEN)
 
 
-def _get_latest_data_points(data):
+def _get_latest_data_points(data, data_point_name):
     data.sort(key=lambda item: item['_timestamp'], reverse=True)
-    return data[0]
+    for data_point in data:
+        if data_point_name in data_point and data_point[data_point_name]:
+            return data_point
+    return {}
 
 
 def _get_stripped_down_data_for_data_point_name_only(
@@ -62,23 +65,22 @@ def _get_stripped_down_data_for_data_point_name_only(
     return new_data
 
 
-def _service_ids_with_latest_data(data):
+def _service_ids_with_latest_data(data, data_point_name):
     for service_data_group in group_by('service_id', data).items():
         yield service_data_group[0], _get_latest_data_points(
-            service_data_group[1])
+            service_data_group[1], data_point_name)
 
 
-def _dashboard_configs_with_latest_data(data):
-    for service_id, latest_data in _service_ids_with_latest_data(data):
+def _dashboard_configs_with_latest_data(data, data_point_name):
+    for service_id, latest_data in _service_ids_with_latest_data(data, data_point_name):  # noqa
         dashboard_configs = admin_api.get_dashboard_by_tx_id(service_id)
         if dashboard_configs:
             yield dashboard_configs[0], latest_data
 
 
 def _get_data_points_for_each_tx_metric(data, transform, data_set_config):
-    for dashboard_config, latest_data in _dashboard_configs_with_latest_data(
-            data):
-        for data_point_name in REQUIRED_DATA_POINTS:
+    for data_point_name in REQUIRED_DATA_POINTS:
+        for dashboard_config, latest_data in _dashboard_configs_with_latest_data(data, data_point_name):  # noqa
             latest_datum = _get_stripped_down_data_for_data_point_name_only(
                 dashboard_config, latest_data, data_point_name)
             # we need to look at, for example,

tests/transformers/fixtures/transactions_explorer_example_data.json

@@ -24,7 +24,27 @@
         "_id": "MjAxMi0wMS0wMSAwMDowMDowMDIwMTMtMDEtMDEgMDA6MDA6MDBiaXMtYW5udWFsLXJldHVybnM=",
         "_month_start_at": "2012-01-01T00:00:00+00:00",
         "_quarter_start_at": "2012-01-01T00:00:00+00:00",
-        "_timestamp": "2012-01-01T00:00:00+00:00",
+        "_timestamp": "2013-01-01T00:00:00+00:00",
+        "_updated_at": "2014-03-19T10:44:32.287000+00:00",
+        "_week_start_at": "2013-12-26T00:00:00+00:00",
+        "cost_per_transaction": 2.63,
+        "digital_cost_per_transaction": 2.36,
+        "digital_takeup": 0.9756123825537215,
+        "end_at": "2013-01-01T00:00:00+00:00",
+        "number_of_digital_transactions": null,
+        "number_of_transactions": 2358738,
+        "period": "year",
+        "service_id": "bis-annual-returns",
+        "total_cost": 6203480.9399999995,
+        "type": "seasonally-adjusted"
+    },
+    {
+        "_day_start_at": "2012-01-01T00:00:00+00:00",
+        "_hour_start_at": "2012-01-01T00:00:00+00:00",
+        "_id": "MjAxMi0wMS0wMSAwMDowMDowMDIwMTMtMDEtMDEgMDA6MDA6MDBiaXMtYW5udWFsLXJldHVybnM=",
+        "_month_start_at": "2012-01-01T00:00:00+00:00",
+        "_quarter_start_at": "2012-01-01T00:00:00+00:00",
+        "_timestamp": "2012-12-12T00:00:00+00:00",
         "_updated_at": "2014-03-19T10:44:32.287000+00:00",
         "_week_start_at": "2013-12-26T00:00:00+00:00",
         "cost_per_transaction": 2.63,

tests/transformers/tasks/test_latest_transaction_explorer_values.py

@@ -116,6 +116,16 @@
         "dashboard_slug": "bis-returns",
         "type": "seasonally-adjusted"
     },
+    {
+        "_id": encode_id('bis-returns', 'number_of_digital_transactions'),
+        "_timestamp": "2012-12-12T00:00:00+00:00",
+        "end_at": "2013-01-01T00:00:00+00:00",
+        "number_of_digital_transactions": 2301214,
+        "period": "year",
+        "service_id": "bis-annual-returns",
+        "dashboard_slug": "bis-returns",
+        "type": "seasonally-adjusted"
+    },
     {
         "_id": encode_id('bis-returns', 'number_of_transactions'),
         "_timestamp": "2013-04-01T00:00:00+00:00",
@@ -172,7 +182,7 @@ def test_compute(self, mock_dashboard_finder, mock_dataset):
             'data-group': 'transactions-explorer',
             'data-type': 'spreadsheet'}})
 
-        assert_that(len(transformed_data), is_(11))
+        assert_that(len(transformed_data), is_(12))
         assert_that(transformed_data, contains_inanyorder(*data_to_post))
 
     @patch("performanceplatform.client.DataSet.from_group_and_type")