add pyodbc output converter for DATETIMEOFFSET (-155)

Author: baldwicc

dbt/adapters/sqlserver/sql_server_connection_manager.py

@@ -1,5 +1,6 @@
 import struct
 import time
+import datetime as dt
 from contextlib import contextmanager
 from itertools import chain, repeat
 from typing import Any, Callable, Dict, Mapping, Optional, Tuple
@@ -233,6 +234,39 @@ def bool_to_connection_string_arg(key: str, value: bool) -> str:
     return f'{key}={"Yes" if value else "No"}'
 
 
+def byte_array_to_datetime(value: bytes) -> dt.datetime:
+    """
+    Converts a DATETIMEOFFSET byte array to a timezone-aware datetime object
+    
+    Parameters
+    ----------
+    value : buffer
+        A binary value conforming to SQL_SS_TIMESTAMPOFFSET_STRUCT
+    
+    Returns
+    -------
+    out : datetime
+    
+    Source
+    ------
+    SQL_SS_TIMESTAMPOFFSET datatype and SQL_SS_TIMESTAMPOFFSET_STRUCT layout:
+    https://learn.microsoft.com/sql/relational-databases/native-client-odbc-date-time/data-type-support-for-odbc-date-and-time-improvements
+    """
+    # unpack 20 bytes of data into a tuple of 9 values
+    tup = struct.unpack("<6hI2h", value)
+
+    # construct a datetime object
+    return dt.datetime(
+        year=tup[0],
+        month=tup[1],
+        day=tup[2],
+        hour=tup[3],
+        minute=tup[4],
+        second=tup[5],
+        microsecond=tup[6],
+        tzinfo=dt.timezone(dt.timedelta(hours=tup[7], minutes=tup[8])),
+    )
+
 class SQLServerConnectionManager(SQLConnectionManager):
     TYPE = "sqlserver"
 
@@ -394,6 +428,10 @@ def add_query(
             else:
                 cursor.execute(sql, bindings)
 
+            # convert DATETIMEOFFSET binary structures to datetime ojbects
+            # https://github.com/mkleehammer/pyodbc/issues/134#issuecomment-281739794
+            connection.handle.add_output_converter(-155, byte_array_to_datetime)
+            
             logger.debug(
                 "SQL status: {} in {:0.2f} seconds".format(
                     self.get_response(cursor), (time.time() - pre)

tests/unit/adapters/sqlserver/test_sql_server_connection_manager.py

@@ -1,4 +1,5 @@
 import datetime as dt
+import struct
 import json
 from unittest import mock
 
@@ -8,6 +9,7 @@
 from dbt.adapters.sqlserver.sql_server_connection_manager import (
     bool_to_connection_string_arg,
     get_pyodbc_attrs_before,
+    byte_array_to_datetime
 )
 from dbt.adapters.sqlserver.sql_server_credentials import SQLServerCredentials
 
@@ -76,3 +78,31 @@ def test_get_pyodbc_attrs_before_contains_access_token_key_for_cli_authenticatio
 )
 def test_bool_to_connection_string_arg(key: str, value: bool, expected: str) -> None:
     assert bool_to_connection_string_arg(key, value) == expected
+
+@pytest.mark.parametrize(
+    "value, expected", [
+        (
+            bytes([
+                0xE5, 0x07,             # year: 2022
+                0x0C, 0x00,             # month: 12
+                0x11, 0x00,             # day: 17
+                0x16, 0x00,             # hour: 22
+                0x16, 0x00,             # minute: 22
+                0x12, 0x00,             # second: 18
+                0x40, 0xE2, 0x01, 0x00, # microsecond: 123456
+                0x02, 0x00, 0x1E, 0x00  # tzinfo: +02:30
+            ]),
+            dt.datetime(
+                2021, 12, 17,
+                22, 22,
+                18, 123456,
+                dt.timezone(dt.timedelta(hours=2, minutes=30))
+            )
+        )
+    ]
+)
+def test_byte_array_to_datetime(value: bytes, expected: dt.datetime) -> None:
+    """
+    
+    """
+    assert byte_array_to_datetime(value) == expected