Async validators?

[omarryhan]

Are there any plans for supporting them?

[omarryhan]

I just looked at how this could be implemented.

On each of its fields, a form calls field.validate() which then calls field._run_validation_chain(). Unfortunately, fields weren't designed with async in mind.

At this point, I think our options are:

1. replace field._run_validation_chain method with the one below (Not sure whether or not asyncio.gather will block here) maybe it won't even work!:

import asyncio
from wtforms.fields.core import Field


class AsyncField(Field):
    def _run_validation_chain(self, form, validators):
        async_validators = [validator for validator in validators if asyncio.iscoroutinefunction(validator)]
        # Probably shouldn't use create_task as it's py37 exclusive.
        tasks = [asyncio.create_task(async_validator(form, field)) for validator in validators]
        return asyncio.gather(*tasks) if tasks else False  # False as in no errors found

2. Provide our own Fields e.g. StringField, EmailField etc. and let all custom fields inherit from AsyncField instead of Field.
3. In SanicForm.validate_on_submit loop over each field in self._fields. If a field has any async validators, validate seperately. Then delete the async validators and continue with normal validation routine.
4. Mehhh, async validators suck...

What do you guys think?