StringConstraints: Bug

[SDAravind]

I see the argument for changing it, but it's a very annoying breaking change to understand, so my instinct is we don't change this, even in a major update.

As for the reason - my guess is that the best explanation is "because that's how it was first done" and there hasn't been a strong (enough) argument to change it.

see below, lowercase/uppercase is set to true and strip whitespaces is set to true. Interestingly, we see the second part of email is always lowercase. This is very strange behavior. Though, I can exclude strip_whitespace as EmailStr takes care of striping whitespaces.

I'm bit confused when to use and not to use strip_whitespace. Should we use strip_whitespace with others params?

from pydantic import BaseModel, EmailStr, StringConstraints
from typing import Annotated

EStr = Annotated[EmailStr, StringConstraints(to_lower=True, strip_whitespace=True)]


class Foo(BaseModel):
    bar: EStr


Foo(bar="[email protected]")
>>>  Foo(bar='[email protected]')

Originally posted by @SDAravind in #8577 (comment)

[RajatRajdeep]

The email validation process relies on the email_validator package.

This validate_email function of the package returns an object with a normalized form of the email address, in which domain is in lowercase.

pydantic/pydantic/networks.py

Line 742 in b844ea7

parts = email_validator.validate_email(email, check_deliverability=False)

[SDAravind]

It's StringConstraints issue after EmailStr validation it has to apply lower/upper case as required but strip_whitespace doesn't make any other parameters work in StringContraints.

[austinyu]

Another example that might be relevant

from pydantic import BaseModel, StringConstraints, NameEmail 
from typing import Annotated

EStr = Annotated[StringConstraints(to_lower=True), NameEmail]

class User(BaseModel):
    email: EStr

user = User(email='Fred Bloggs <[email protected]>')
print(user)

Result

# Expected
email=NameEmail(name='Fred Bloggs', email='[email protected]')
# Actual
email=NameEmail(name='Fred Bloggs', email='[email protected]')

[sydney-runkle]

@SDAravind,

Thanks for reporting this in a separate issue. I've added this to our upcoming milestone!