handle timezones

sql.py

@@ -2,21 +2,40 @@
 from pathlib import Path
 from datetime import datetime
 from itertools import islice
-from typing import Type, NamedTuple, Union
+from typing import Type, NamedTuple, Union, Optional
 import logging
 
 from location import _load_locations, Location, get_logger
+import sqlalchemy # type: ignore
 import sqlalchemy as sa # type: ignore
 
 from kython import ichunks
 
 
+from kython.py37 import fromisoformat
+
+# TODO move to some common thing?
+class IsoDateTime(sqlalchemy.TypeDecorator):
+    # TODO can we use something more effecient? e.g. blob for encoded datetime and tz? not sure if worth it
+    impl = sqlalchemy.types.String
+
+    # TODO optional?
+    def process_bind_param(self, value: Optional[datetime], dialect) -> Optional[str]:
+        if value is None:
+            return None
+        return value.isoformat()
+
+    def process_result_value(self, value: Optional[str], dialect) -> Optional[datetime]:
+        if value is None:
+            return None
+        return fromisoformat(value)
+
+
 def _map_type(cls):
     tmap = {
         str: sa.String,
         float: sa.Float,
-        datetime: sa.types.TIMESTAMP(timezone=True), # TODO tz?
-        # TODO FIXME utc seems to be lost.. doesn't sqlite support it or what?
+        datetime: IsoDateTime,
     }
     r = tmap.get(cls, None)
     if r is not None:
@@ -30,7 +49,8 @@ def _map_type(cls):
             return _map_type(elems[0]) # meh..
     raise RuntimeError(f'Unexpected type {cls}')
 
-
+# TODO to strart with, just assert utc when serializing, deserializing
+# TODO how to use timestamp as key? just round it?
 
 def make_schema(cls: Type[NamedTuple]): # TODO covariant?
     res = []
@@ -71,7 +91,7 @@ def test(tmp_path):
     tdir = Path(tmp_path)
     tdb = tdir / 'test.sqlite'
     test_limit = 100
-    test_src = Path('/L/tmp/loc/LocationHistory.json')
+    test_src = Path('/L/tmp/LocationHistory.json')
 
     # TODO meh, double loading, but for now fine
     with test_src.open('r') as fo:
@@ -80,10 +100,7 @@ def test(tmp_path):
     cache_locs(source=test_src, db_path=tdb, limit=test_limit)
     cached_locs = list(iter_db_locs(tdb))
     assert len(cached_locs) == test_limit
-    def FIXME_tz(locs):
-        # TODO FIXME tzinfo...
-        return [x._replace(dt=x.dt.replace(tzinfo=None)) for x in locs]
-    assert FIXME_tz(real_locs) == FIXME_tz(cached_locs)
+    assert real_locs == cached_locs
 
 def main():