JavaScript negative timestamp are not supported

[mlbiche]

Bug

When parsing a JavaScript positive timestamp (number of milliseconds since EPOCH), pydantic parses it properly. However, for a negative JavaScript timestamp (before 1st January 1970), a date value out of range error is thrown.

  File "pydantic/main.py", line 447, in pydantic.main.BaseModel.parse_obj
  File "pydantic/main.py", line 336, in pydantic.main.BaseModel.__init__
  File "pydantic/main.py", line 887, in pydantic.main.validate_model
  File "pydantic/fields.py", line 549, in pydantic.fields.ModelField.validate
  File "pydantic/fields.py", line 704, in pydantic.fields.ModelField._validate_singleton
  File "pydantic/fields.py", line 711, in pydantic.fields.ModelField._apply_validators
  File "pydantic/class_validators.py", line 313, in pydantic.class_validators._generic_validator_basic.lambda11
  File "pydantic/datetime_parse.py", line 169, in pydantic.datetime_parse.parse_datetime
  File "pydantic/datetime_parse.py", line 80, in pydantic.datetime_parse.from_unix_seconds
OverflowError: date value out of range

Version

Output of python -c "import pydantic.utils; print(pydantic.utils.version_info())":

             pydantic version: 1.5.1
            pydantic compiled: True
                 install path: /Users/thibaud/Documents/Programmation/Scopyleft/Terrapeutes/aposto-server/venv/lib/python3.7/site-packages/pydantic
               python version: 3.7.3 (default, Mar  6 2020, 22:34:30)  [Clang 11.0.3 (clang-1103.0.32.29)]
                     platform: Darwin-19.5.0-x86_64-i386-64bit
     optional deps. installed: ['typing-extensions', 'email-validator']

Code example

The following code raises the describe error (while it would correctly work with { "jsTimestamp": 1118102400000 }).

from datetime import datetime

from pydantic import BaseModel


class MyModel(BaseModel):
    jsTimestamp: datetime

MyModel.parse_obj({ "jsTimestamp": -1118102400000 })

Possible solution

A solution would be to update the from_unix_seconds function in datetime_parse.py to compare seconds with MS_WATERSHED as absolute value.

[samuelcolvin]

Happy to accept a PR to fix this.

I guess we should:

• raise the correct error resulting in a validation error if the datetime is out of bounds
• accept negative timestamps if they result in valid datetimes - there's nothing implicitly wrong with the unix timestamp of -1. Stuff happened before 1970 apparently.
• comparing with MS_WATERSHED as an absolute number makes sense I suppose, we would just need to update the docs to be explicit.

[mlbiche]

I don't get this :

* raise the correct error resulting in a validation error if the datetime is out of bounds

For the rest, everything is running fine and ready for PR

[samuelcolvin]

I think it might be fine, I just meant:

make sure passing timestamps like 1_000_000_000_000_000 or -100_000_000_000_000 cause sensible validation errors not other exceptions.

[mlbiche]

Yes, it runs fine with these timestamps. The generated datetime does not match with the real date as these timestamps are greater than MS_WATERSHED but it is parsed without any exception.

[samuelcolvin]

Best to submit a PR and we can discuss from there.