newforms URL validation rejects leading/trailing space

[Antti Kaihola]

URL fields raise a validation error if a valid URL has leading or trailing spaces. A string with only spaces also raises an error instead of being interpreted as empty when the field is not required.

>>> from django import newforms as forms
>>> u=forms.URLField(required=False)
>>> u.clean('www.djangoproject.com')
u'http://www.djangoproject.com'
>>> u.clean('  http://www.djangoproject.com/')
ValidationError: [u'Enter a valid URL.']
>>> u.clean('http://www.djangoproject.com/  ')
ValidationError: [u'Enter a valid URL.']
>>> u.clean('  ')
ValidationError: [u'Enter a valid URL.']

Django should first strip leading and trailing spaces from the URL before validating it.

Rationale:

• browser address fields strip URLs
• Python's urllib and urllib2 open URLs with leading/trailing spaces correctly
• leading/trailing spaces and only-space strings are hard to spot for non-experienced web users
• "Be liberal in what you accept, and conservative in what you send"

[Antti Kaihola]

patch: newforms.URLField ignores leading/trailing space

[Antti Kaihola]

revised patch: handles None correctly, includes unit tests

[Ramiro Morales]

See also #6362 for a more general proposal.

[Jacob]

Yeah, #6362 is the bigger issue here. It wouldn't make sense to treat URLs differently from other field types -- consistency, consistency, consistency.