[BUG] Query(regex) does not work for date types

Describe the bug I would like to be able to make some data filter by GET parameter which is date

/api/foo?from_date=2019-01-01

And I want specifically it to be in YYYY-MM-DD format

To Reproduce Steps to reproduce the behavior: 1. I made the following parameter with query and regex: def filter_order(from_date: date = Query(..., regex=r'\d{4}-\d{2}-\d{2}')

Expected behavior when i query /api/foo?from_date=1 I expect a validation error

instead my date is valid and equal to date(1970, 1, 1)

[tiangolo]

@vitalik if you use a date or datetime type, then Pydantic uses it to handle data parsing. And anything you pass to Query() is used only for documentation.

If you use str, then the regex in Query(..., regex="") is used for documentation AND regex.

If you want to have something constrained to some types of dates only, you could declare the parameter as str with the regex. And then if you want to have a date from it, you could put that in a dependency.

E.g.

from datetime import datetime, date

from fastapi import FastAPI, Query, Depends

app = FastAPI()


def strict_date(
    from_date: str = Query(..., regex=r"\d{4}-\d{2}-\d{2}", format="date")
) -> date:
    dt = datetime.strptime(from_date, "%Y-%m-%d")
    return dt.date()


@app.get("/")
def filter_order(from_date: date = Depends(strict_date)):
    return from_date.isoformat()

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