Pydantic: Validation: preserve invalid data

[olexandr-klymenko]

Feature Request

In order to be able to find broken records in the database, it would be great to be able to get full data of invalid item in the ValidationError traceback output.

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

pydantic version: 1.4
            pydantic compiled: True
                 install path: /home/oklymenko/.virtualenvs/zakaz-commerceman-api/lib/python3.8/site-packages/pydantic
               python version: 3.8.0 (default, Oct 21 2019, 13:32:28)  [GCC 7.4.0]
                     platform: Linux-5.3.0-46-generic-x86_64-with-glibc2.27
     optional deps. installed: []

from datetime import datetime

from pydantic import BaseModel, ValidationError


class SomeResponse(BaseModel):
    class Config:
        invalid_model_full_data = True

    id: str
    name: str
    start_datetime: datetime
    end_datetime: datetime


imvalid_data = {
    "id": "123123",
    "name": ["some_name"],
    "start_datetime": 4,
    "end_datetime": 2,
}

try:
    SomeResponse(**imvalid_data)
except ValidationError as e:
    print(e)

"""
1 validation error for SomeResponse
name
  str type expected (type=type_error.str)
full_data
  {
    "id": "123123",
    "name": ["some_name"],
    "start_datetime": 4,
    "end_datetime": 2,
}
"""
...

[samuelcolvin]

I think that's reasonable if it's easy to implement.

Let's do it as part of v2.

[StephenBrown2]

I like this idea.

At the risk of bikeshedding, I'd like to see this as an attribute on the ValidationError raised (original/raw_data maybe?), rather than by default in the message, as I may be validating large objects and don't want to see the whole thing in every case.

If it's adding anything to the default message string, I would presume it would be under a "received" or "got" key and displayed next to/at the end of the expected line.

[samuelcolvin]

total agree, that's why I didn't add it earlier, but I can see many scenarios where access to that data would be useful.

[olexandr-klymenko]

@samuelcolvin @StephenBrown2 guys, please, review