Sites.domain should not contain whitespace

[Jason Novinger]

Having space characters in the domain field of the Site model causes problems when using an instance to generate links (e.g. Share on Facebook).

[Aymeric Augustin]

I agree that spaces in domain names are invalid.

However, Django avoids "magic auto-fix", because it quickly becomes auto-break for some expectations.

If would be better to implement a clean_fields method in the Site model.

[Christopher Medrela]

I'd implemented clean method instead of clean_fields - it's much more simpler (you've not to call parent).

Another issue is that my implementation check if domain doesn't contain spaces, but it doesn't check other whitespaces (for example '\r'). Is it necessary?

If it is, we can do it in a few ways:

if self.domain != (self.domain.translate(None, string.whitespace)):

or

if all(map(lambda whitespace: whitespace not in self.domain, string.whitespace)):

or

if all(map(lambda whitespace: self.domain.find(whitespace) == -1, string.whitespaces)):

or

if re.search('\s', self.domain):

The first three are ugly. The last one is the best, but it's slow (the pattern '\s' must be compiled each time - the solution is to cache compiled pattern).

[Horst Gutmann]

Personally, I believe that validating regarding spaces alone should be sufficient (unless we want to go for an all-out domain-name validation) but the current patch marks the whole model as invalid and not just the domain field. Also, since this is a user-facing validation message, it should be localized.

So the question raised above remains: Do we only need space-validation or should we go for an all-out domain name validation for this field?

[Mathijs de Bruin]

Doing domain-name validation 'the right way' leads to a lot of added complexity in the code and, what's worse: the risk of false negatives. People not being able to add a reference to their own site is *not* what we want.

As for the validation: the error can and should happen at the field level by adding the validator to validators for the database field. For this an instance of Django's RegexValidator can be used.

[Horst Gutmann]

Added a pull request: ​https://github.com/django/django/pull/828

I opted with a separate function to make space for documenting the simple nature of the validation.

[Ben Kornrath]

I wonder if the error message should be geared more towards non-technical users and (to me) 'whitespace' feels like a technical term. What do you think about this for an error message?: "The domain name cannot contain any spaces or tabs."

[Horst Gutmann]

@benkonrath sounds good to me. Amended the pull-request :)

[Horst Gutmann <hgutmann@…>]

In c7294614795a3c0b3a872707bbea93733ef2077d:

Fixed #17320 -- Added whitespace validation to the Site.domain field

[Florian Apolloner <florian@…>]

In 5e52dc2ade8b040f2cee743a108267562baf117e:

Merge pull request #828 from zerok/tickets/17320

Fixed #17320 -- Added whitespace validation to Site.domain field

[Florian Apolloner <florian@…>]

In b88bf9f1257080d5dcc08792c8e57118fb183987:

Fixed python 3 support. Refs #17320