Add support for URL validator options to URLField

[psjamesh]

It would be useful it the URLField class supported passing options to the underlying URLValidator.

For example, I would like to verify that a URL is HTTPS only. It would be helpful to define this in the field, eg:

url = URLField(url_validator_options={"schemes": ["https"]})

This would be a very simple change, adding flexibility to the field to avoid including extra validation elsewhere in the application.

class URLField(CharField):
    default_error_messages = {"invalid": _("Enter a valid URL.")}

    def __init__(self, url_validator_options: dict = {}, **kwargs):
        super().__init__(**kwargs)

        validator = URLValidator(
            message=self.error_messages["invalid"], **url_validator_options
        )

        self.validators.append(validator)

[nchz]

For your particular example (allow only HTTPS) there's a clean and simple solution that doesn't require modifications in the URLField class:

from django.core.validators import URLValidator
from rest_framework import serializers

class MySerializer(serializers.Serializer):
    some_url = serializers.URLField(
        validators=[URLValidator(schemes=["https"])],
    )

assert not MySerializer(data={"some_url": "http://example.com"}).is_valid()
assert MySerializer(data={"some_url": "https://example.com"}).is_valid()

Nevertheless, you made me realize that this works because your schemes of interest are a subset of the default schemes of URLValidator. But there's something interesting: If someone needs to validate, say, s3://bucket/prefix the above code will never work, because both validators (the default one and the explicitly set in MySerializer) will run, and the sets of schemes are disjoint.

I propose this answer because it may help in your use case, and I also give +1 because the feature seems to be useful in other scenarios.

[psjamesh]

Thanks Ignacio, that's a good solution to my problem.