Fixed #18119 -- Added a DomainNameValidator validator.

[nmenezes0]

Trac ticket number

ticket-18119

Branch description

Provide a concise overview of the issue or rationale behind the proposed changes.
This ticket adds a DomainNameValidator to validate International domain names. This validator takes a flag is_idna (defaults to True) - to determine whether or not we should use non-ASCII international domain names.

This builds on the existing PR with some changes: not using IP addresses (don't think they are part of a domain name), removing changes to docs as out of date (not sure what updates are needed here now?), changes to the tests and how they were written, reusing the regex in URLValidator.

The ticket in Trac suggests that the regex could be reused elsewhere in the codebase. I have reused it in the URLValidator, but I couldn't see how to use it in django/core/mail/message.py or django/utils/html.py.

Checklist

• This PR targets the main branch.
• The commit message is written in past tense, mentions the ticket number, and ends with a period.
• I have checked the "Has patch" ticket flag in the Trac system.
• I have added or updated relevant tests.
• I have added or updated relevant docs, including release notes if applicable.
• For UI changes, I have attached screenshots in both light and dark modes. - N/A

I wasn't sure what changes I should make to the documentation.

[sarahboyce]

Thank you for this Nina ⭐

removing changes to docs as out of date (not sure what updates are needed here now?)

All new features need some docs and a release note, so this is roughly what I am expecting:

• Add DomainNameValidator to docs/ref/validators.txt with .. versionadded:: 5.1
• Add a reference to this change in the 5.1 release notes

[nmenezes0]

Thanks Sarah - docs now updated.

[nmenezes0]

Thanks @felixxm - docs now updated following comments.

[sarahboyce]

Thank you @nmenezes0 ⭐ I have a few more comments.
Please also squash this to a single commit 👍

[nmenezes0]

Thanks @sarahboyce - I've made those changes and squashed to a single commit.

[nmenezes0]

I'm not sure why some of the checks are failing. The error is "commit changed" - potentially due to me pushing the squashed commit?

[sarahboyce]

Thank you for the updates @nmenezes0, we're really close ⭐

I'm not sure why some of the checks are failing. The error is "commit changed" - potentially due to me pushing the squashed commit?

Don't worry about this, sounds unrelated to your changes

The ticket in Trac suggests that the regex could be reused elsewhere in the codebase. I have reused it in the URLValidator, but I couldn't see how to use it in django/core/mail/message.py or django/utils/html.py.

Read through the original comment made by @claudep 12 years ago.

• It's still valid that we could chose to use this validation in other areas of the codebase.
• I don't think refactoring to include this is in scope of this ticket, however we should make sure it's defined in a good place.
• I'm not sure which __init__ is being referred to in the comment and I don't get circular imports if I was to import DomainNameValidator to the mentioned files.

@claudep can you clarify where you think DomainNameValidator should be defined or whether it is correct to be in django/core/validators.py?
I think it is ok to be defined here but I might be missing something 👍

[nmenezes0]

Thanks @sarahboyce - have commited those docs changes - I assume I should squash into one commit again (will do that later).