refactor last_update to support mult-index

Author: Adrian Teng

arctic/store/bitemporal_store.py

@@ -10,7 +10,7 @@
 
 
 class BitemporalStore(object):
-    """ A versioned pandas DataFrame store. (currently only supports single index df)
+    """ A versioned pandas DataFrame store.
 
     As the name hinted, this holds versions of DataFrame by maintaining an extra 'insert time' index internally.
     """
@@ -22,8 +22,8 @@ def __init__(self, version_store, observe_column='observed_dt'):
         version_store : `VersionStore`
             The version store that keeps the underlying data frames
         observe_column : `str`
-            Column name for the datetime index that represents the insertion time of a row of data. This column is
-            internal to this store.
+            Column name for the datetime index that represents the insertion time of a row of data. Unless you intent to
+            read raw data out, this column is internal to this store.
         """
         self._store = version_store
         self.observe_column = observe_column
@@ -48,16 +48,17 @@ def read(self, symbol, as_of=None, raw=False, **kwargs):
         BitemporalItem namedtuple which contains a .data and .metadata element
         """
         item = self._store.read(symbol, **kwargs)
+        last_updated = max(item.data.index.get_level_values(self.observe_column))
         if raw:
             return BitemporalItem(symbol=symbol, library=self._store._arctic_lib.get_name(), data=item.data,
                                   metadata=item.metadata,
-                                  last_updated=max(item.data.index, key=lambda x: x[1]))
+                                  last_updated=last_updated)
         else:
             index_names = list(item.data.index.names)
             index_names.remove(self.observe_column)
             return BitemporalItem(symbol=symbol, library=self._store._arctic_lib.get_name(),
                                   data=groupby_asof(item.data, as_of=as_of, dt_col=index_names, asof_col=self.observe_column),
-                                  metadata=item.metadata, last_updated=max(item.data.index, key=lambda x: x[1]))
+                                  metadata=item.metadata, last_updated=last_updated)
 
     def update(self, symbol, data, metadata=None, upsert=True, as_of=None, **kwargs):
         """ Append 'data' under the specified 'symbol' name to this library.

tests/integration/store/test_bitemporal_store.py

@@ -44,6 +44,12 @@ def test_read_ts_raw(bitemporal_library):
                                                       2012-11-08 17:06:11.040 |  2015-05-01 |  3.0""", num_index=2))
 
 
+def test_last_update(bitemporal_library):
+    bitemporal_library.update('spam', ts1, as_of=dt(2015, 1, 1))
+    bitemporal_library.update('spam', ts1, as_of=dt(2015, 1, 2))
+    assert bitemporal_library.read('spam').last_updated == dt(2015, 1, 2)
+
+
 def test_existing_ts_update_and_read(bitemporal_library):
     bitemporal_library.update('spam', ts1)
     bitemporal_library.update('spam', ts1_update[-1:])
@@ -245,6 +251,7 @@ def test_multi_index_update(bitemporal_library):
                           2012-11-08 17:06:11.040 | SPAM Index |  3.0
                           2012-12-08 17:06:11.040 |  EGG Index |
                           2012-12-08 17:06:11.040 | SPAM Index |  4.0""", num_index=2)
-    bitemporal_library.update('spam', ts)
-    bitemporal_library.update('spam', ts2)
+    bitemporal_library.update('spam', ts, as_of=dt(2015, 1, 1))
+    bitemporal_library.update('spam', ts2, as_of=dt(2015, 1, 2))
     assert_frame_equal(expected_ts, bitemporal_library.read('spam').data)
+    assert bitemporal_library.read('spam').last_updated == dt(2015, 1, 2)