Fixing get_last without date qualifier.

Author: chsou

c8y_api/model/measurements.py

@@ -258,10 +258,15 @@ def get_last(self, type=None, source=None, fragment=None, value=None, series=Non
 
         :returns:  Measurement object
         """
+        # at least one date qualifier is required for this query to function,
+        # so we enforce the 'after' filter if nothing else is specified
+        after = None
+        if not before and not min_age:
+            after = '1970-01-01'
         base_query = self._build_base_query(type=type, source=source,
-                                            fragment=fragment, value=value, series=series,
+                                            fragment=fragment, value=value, series=series, after=after,
                                             before=before, min_age=min_age, reverse=True, page_size=1)
-        m = Measurement.from_json(self._get_page(base_query, "1")['measurements'][0])
+        m = Measurement.from_json(self._get_page(base_query, "1")[0])
         m.c8y = self.c8y  # inject c8y connection into instance
         return m
 

sample/measurements.py

@@ -49,9 +49,17 @@
     print(f"Created measurement #{m1_created.id} with time {m1_created.time}.")
     assert time != m1_created.time
 
+# get the last measurement
+my_type = 'c8y_DemoMeasurement'
+print(f"\nListing the latest Measurement for type '{my_type}' ...")
+m = c8y.measurements.get_last(type=my_type)
+v = m.c8y_DemoMeasurement.Iterations.value
+u = m.c8y_DemoMeasurement.Iterations.unit
+t = m.time
+print(f"  Got measurement at {t}: {v} {u}")
+
 # querying the database by type
 # other filters are possible: source, fragment, date
-my_type = 'c8y_DemoMeasurement'
 print(f"\nListing all Measurements for type '{my_type}' ...")
 for m in c8y.measurements.select(type=my_type, after=run_at, reverse=True):
     v = m.c8y_DemoMeasurement.Iterations.value