Unable to identify user with a trait that has the value "Nan"

[matthewelwell]

Describe the bug

Setting a trait to a string of "Nan" when identifying a user causes a 502 error in the Edge API and will cause the detail view of the identity to fail to load in the Flagsmith dashboard.

To Reproduce

curl --location 'https://edge.api.flagsmith.com/api/v1/identities' \
--header 'Content-Type: application/json' \
--header 'X-Environment-Key: <ENV_KEY>' \
--data '{
    "identifier": "identity",
    "traits": [
        {
            "trait_key": "my_trait",
            "trait_value": "Nan"
        }
    ]
}'

Expected behavior

1. The trait is stored as a string and a successful response is returned from the Edge API
2. The identity detail page loads in the Flagsmith dashboard and shows the trait as a string

Screenshots

N/a

How are you running Flagsmith?

• Self Hosted with Docker
• Self Hosted with Kubernetes
• SaaS at flagsmith.com
• Some other way

Additional context

A quick fix here is to set the trait value to e.g. "Nan_"

[matthewelwell]

Seems like this is some very odd behaviour from pydantic. Here is a minimal script to reproduce the issue:

import typing
from pydantic import BaseModel


class MyModel(BaseModel):
    foo: typing.Union[float, str]


o = MyModel.parse_obj({"foo": "Nan"})

assert o.foo == "Nan"

This will throw an AssertionError