OpenBB-finance/OpenBB · error · ValueError

Start and end dates must be in the same Congress session.

Error message

Start and end dates must be in the same Congress session.

What it means

When both start_date and end_date are supplied to get_bills_by_type, the helper derives a single congress number from each date's year and requires them to match, because the underlying URL addresses one Congress at a time (/bill/{congress}/{bill_type}). A date pair spanning a Congress boundary (odd-numbered January, e.g. 2023-01-03) cannot be served by one request and raises ValueError.

Source

Thrown at openbb_platform/providers/congress_gov/openbb_congress_gov/utils/helpers.py:213

        raise ValueError(
            f"Invalid bill type: {bill_type}. Must be one of {', '.join(BillTypes)}."
        )

    api_key = check_api_key()

    if start_date is None and end_date is None and congress is None:
        congress = year_to_congress(datetime.now().year)
    elif congress is None and start_date is not None:
        congress = year_to_congress(dateType.fromisoformat(start_date).year)
    elif congress is None and end_date is not None and start_date is None:
        congress = year_to_congress(dateType.fromisoformat(end_date).year)
    elif start_date is not None and end_date is not None:
        start_year = dateType.fromisoformat(start_date).year
        end_year = dateType.fromisoformat(end_date).year
        congress_start = year_to_congress(start_year)
        congress_end = year_to_congress(end_year)
        if congress_start != congress_end:
            raise ValueError(
                "Start and end dates must be in the same Congress session."
            )
        congress = congress_start

    if congress is None:
        congress = year_to_congress(datetime.now().year)

    url = (
        f"{base_url}bill/{congress}/{bill_type}"
        + (f"?fromDateTime={start_date + 'T00:00:00Z'}" if start_date else "")
        + (f"&toDateTime={end_date + 'T23:59:59Z'}" if end_date else "")
        + f"?limit={limit if limit is not None else 10}"
        + (f"&offset={offset}" if offset else "")
        + f"&sort=updateDate+{sort_by}"
        + f"&format=json&api_key={api_key}"
    )

    return await amake_request(url)

View on GitHub (pinned to 3e071fcc2c)

Solutions

  1. Split the range at the Congress boundary and issue one request per Congress (117th and 118th), then concatenate
  2. Narrow the range so both dates fall in the same Congress
  3. Pass congress explicitly with dates fully inside that Congress's session

Example fix

# before
res = await get_bills_by_type(bill_type='hr', start_date='2022-06-01', end_date='2023-06-01')

# after
res = []
for congress in (117, 118):
    res += (await get_all_bills(congress=congress, bill_type='hr'))['bills']
Defensive patterns

Strategy: validation

Validate before calling

from datetime import date

def spans_one_congress(start: str, end: str) -> bool:
    sy, ey = date.fromisoformat(start).year, date.fromisoformat(end).year
    # Congress N covers [1935 + 2*(N-74), +1]; same Congress iff same derived number
    return (74 + (sy - 1935) // 2) == (74 + (ey - 1935) // 2)

Try / catch

try:
    res = await get_bills_by_type(bill_type='hr', start_date=s, end_date=e)
except ValueError as ex:
    if 'same Congress session' in str(ex):
        res = []
        for c in {year_to_congress(date.fromisoformat(d).year) for d in (s, e)}:
            res += await get_all_bills(congress=c, bill_type='hr')
    else:
        raise

Prevention

When it happens

Trigger: start_date='2022-06-01', end_date='2023-06-01' (117th vs 118th Congress); any range covering two January 3rds; a full-year range like 2023-01-01..2024-12-31.

Common situations: Default reporting windows (last 12/18 months) that cross a Congress rollover; users assuming date ranges work like other OpenBB providers that split queries automatically.

Related errors

AI-assisted analysis of OpenBB-finance/OpenBB@3e071fcc2c (2026-08-14). Data as JSON: /api/errors/fd19dbb2f9cf552c. Report an issue: GitHub.