QueryString: empty string is not validated like string with length > 1

[kopax-polyconseil]

Actual Behavior

If I have a form filled validated with query string and wrong values, such as:

Wrong string values

This will trigger the validation:

?order=fewfewfew&sort=fewfew

Wrong string values

This will not trigger the validation

?order=&sort=

Instead you'll have this 500 error:

ERROR:pcapi.routes.error_handlers.generic_error_handlers:Unexpected error on method=GET url=http://localhost:5001/backofficev3/pro/validation/user-offerer?order=&sort=: type object 'UserOfferer' has no attribute ""

Expected Behavior

I expect empty string and string with length to have the same behavior

Reproduction

Fields:

order = wtforms.HiddenField("order", default="desc", validators=(wtforms.validators.Optional(),))
sort = wtforms.HiddenField("sort", default="dateCreated", validators=(wtforms.validators.Optional(),))

Validators:

def validate_order(self, order: wtforms.HiddenField) -> wtforms.HiddenField:
    if order.data:
        order.data = order.data.lower()
        if order.data not in ("asc", "desc"):
            raise wtforms.validators.ValidationError("Order can only be asc or desc")
    return order

def validate_sort(self, sort: wtforms.HiddenField) -> wtforms.HiddenField:
    if sort.data:
        if sort.data not in ("dateCreated"):
            raise wtforms.validators.ValidationError(f"Sorting by {sort.data} is not allowed")
    return sort

Environment

• Python version: 3.10
• wtforms version: 3.0.1

[azmeuk]

The 500 error you refer to does not seem related to wtforms, or at least you did not provide enough context so I can help you. Have you a traceback somewhere?

I will close the ticket for now, if you think this is actually related with wtforms, we can re-open the bug if you provide a minimal reproducible example, ideally something that one can just copy/paste in a python terminal and that demonstrates your issue. Like:

>>> import wtforms
>>> class F(wtforms.Form):
...     order = wtforms.HiddenField()
...     sort = wtforms.HiddenField()
>>> f = F(...)
>>> f.validate()
...