move iso_range_to_ts_range to datetime_utils.py

This function is used by db_utils but might be better categorized in datetime_utils.
Previously called`get_ts_range`, its new name is `iso_range_to_ts_range`, since I thought that was more descriptive.

-- Also, I noticed `arrow` was imported in db_utils twice, so i fixed that while I was here

utils/datetime_utils.py

@@ -1,7 +1,32 @@
+import arrow
+
+MAX_EPOCH_TIME = 2 ** 31 - 1
+
+
+def iso_range_to_ts_range(start_date: str, end_date: str, tz: str):
+    """
+    Returns a tuple of (start_ts, end_ts) as epoch timestamps, given start_date and end_date in
+    ISO format and the timezone mode in which the dates should be resolved to timestamps ('utc' or 'local')
+    """
+    start_ts, end_ts = None, MAX_EPOCH_TIME
+    if start_date is not None:
+        if tz == 'utc':
+            start_ts = arrow.get(start_date).timestamp()
+        elif tz == 'local':
+            start_ts = arrow.get(start_date, tzinfo='local').timestamp()
+    if end_date is not None:
+        if tz == 'utc':
+            end_ts = arrow.get(end_date).replace(
+                hour=23, minute=59, second=59).timestamp()
+        elif tz == 'local':
+            end_ts = arrow.get(end_date, tzinfo='local').replace(
+                hour=23, minute=59, second=59).timestamp()
+    return (start_ts, end_ts)
+
+
 def iso_to_date_only(*iso_strs: str):
     """
     For each ISO date string in the input, returns only the date part in the format 'YYYY-MM-DD'
     e.g. '2021-01-01T00:00:00.000Z' -> '2021-01-01'
     """
     return [iso_str[:10] if iso_str else None for iso_str in iso_strs]
-

utils/db_utils.py

@@ -2,8 +2,6 @@
 import arrow
 from uuid import UUID
 
-import arrow
-
 import pandas as pd
 import pymongo
 
@@ -15,26 +13,7 @@
 
 from utils import constants
 from utils import permissions as perm_utils
-
-MAX_EPOCH_TIME = 2 ** 31 - 1
-
-def get_ts_range(start_date: str, end_date: str, tz: str):
-    """
-    Returns a tuple of (start_ts, end_ts) as timestamps, given start_date and end_date in ISO format
-    and the timezone mode in which the dates should be resolved to timestamps ('utc' or 'local')
-    """
-    start_ts, end_ts = None, MAX_EPOCH_TIME
-    if start_date is not None:
-        if tz == 'utc':
-            start_ts = arrow.get(start_date).timestamp()
-        elif tz == 'local':
-            start_ts = arrow.get(start_date, tzinfo='local').timestamp()
-    if end_date is not None:
-        if tz == 'utc':
-            end_ts = arrow.get(end_date).replace(hour=23, minute=59, second=59).timestamp()
-        elif tz == 'local':
-            end_ts = arrow.get(end_date, tzinfo='local').replace(hour=23, minute=59, second=59).timestamp()
-    return (start_ts, end_ts)
+from utils.datetime_utils import iso_range_to_ts_range
 
 def query_uuids(start_date: str, end_date: str, tz: str):
     # As of now, time filtering does not apply to UUIDs; we just query all of them.
@@ -74,7 +53,7 @@ def query_uuids(start_date: str, end_date: str, tz: str):
     return df
 
 def query_confirmed_trips(start_date: str, end_date: str, tz: str):
-    (start_ts, end_ts) = get_ts_range(start_date, end_date, tz)
+    (start_ts, end_ts) = iso_range_to_ts_range(start_date, end_date, tz)
     ts = esta.TimeSeries.get_aggregate_time_series()
     # Note to self, allow end_ts to also be null in the timequery
     # we can then remove the start_time, end_time logic
@@ -157,7 +136,7 @@ def query_demographics():
 
 def query_trajectories(start_date: str, end_date: str, tz: str):
 
-    (start_ts, end_ts) = get_ts_range(start_date, end_date, tz)
+    (start_ts, end_ts) = iso_range_to_ts_range(start_date, end_date, tz)
     ts = esta.TimeSeries.get_aggregate_time_series()
     entries = ts.find_entries(
         key_list=["analysis/recreated_location"],