Before:
cur.execute("SELECT CURRENT YEAR TO SECOND ...")
cur.fetchone() # → (b'\xc7\x14\x1a\x05\x04...',) raw BCD bytes
After:
cur.execute("SELECT CURRENT YEAR TO SECOND ...")
cur.fetchone() # → (datetime.datetime(2026, 5, 4, 12, 34, 56),)
Decoder picks the right Python type by qualifier:
YEAR/MONTH/DAY-only → datetime.date
HOUR/MIN/SEC-only → datetime.time
spans across both → datetime.datetime
Wire format (per IfxToJavaDateTime + Decimal.init treating as packed BCD):
byte[0] = sign + biased exponent (in base-100 digit pairs)
byte[1..] = BCD digit pairs: YYYY (2 bytes) + MM + DD + HH + MI + SS + FFFFF
Qualifier extraction from column descriptor:
encoded_length = (digit_count << 8) | (start_TU << 4) | end_TU
TU codes: YEAR=0, MONTH=2, DAY=4, HOUR=6, MIN=8, SEC=10,
FRAC1=11..FRAC5=15
Verified against four DATETIME columns of different qualifiers in
one tuple — see test_datetime_multiple_columns_in_one_row:
YEAR TO SECOND → datetime.datetime(2026, 5, 4, 12, 34, 56)
YEAR TO DAY → datetime.date(2026, 5, 4)
HOUR TO SECOND → datetime.time(12, 34, 56)
YEAR TO FRACTION(3) → datetime.datetime(...)
Module changes:
src/informix_db/converters.py:
+ _decode_datetime(raw, encoded_length) — qualifier-driven BCD walk
+ TU constants (_TU_YEAR, _TU_MONTH, ..., _TU_SECOND)
src/informix_db/_resultset.py:
+ DATETIME row-decoder branch — computes width from digit_count
in encoded_length high byte, calls _decode_datetime with the
packed qualifier so it can pick the right Python type
Tests: 40 unit + 70 integration (7 new DATETIME tests) = 110 total,
all green, ruff clean. Tests cover:
- YEAR TO SECOND → datetime.datetime
- YEAR TO DAY → datetime.date
- HOUR TO SECOND → datetime.time
- CURRENT YEAR TO FRACTION(3) → datetime.datetime
- Mixed qualifiers in one row
- DATETIME stored in a real table column (round-trip via SELECT)
- NULL DATETIME → Python None
DATETIME parameter binding (encoder) is Phase 6.x — same status as
DECIMAL encoder.
Ryan Malloy
6819dd4cb0