HashedFilesMixin.patterns should limit URL matches to their respective filetypes

[alex.ehlke@…]

HashedFilesMixin contains a patterns property which maps file extensions to regex patterns. This works great for the default case that Django ships with "*.css" as the only filetype, but results in surprising behavior once extended with multiple filetypes. I would expect the regex patterns to only apply to the filetype they're categorized under, but once I added "*.js" to patterns (via subclassing), the CSS rules also applied to my JS files.

My use-case of extending this is to add URL rewriting to JS source map references, e.g. //# sourceMappingURL=foo.js.map which can appear at the end of JS files. I need to be able to rewrite these URLs in the same way that Django's staticfiles can rewrite URLs in CSS, for e.g. adding hashes to filenames.

Once I tried extending patterns with this:

    patterns = HashedFilesMixin.patterns + (
        ("*.js", (
            (r"""(//# sourceMappingURL=(\s*))""", """//# sourceMappingURL=%s"""),
        )),
    )

The surprising and broken behavior was that Django tried to rewrite "URLs" for this JS (from Backbone.js): this.loadUrl(window.location.hash), which matched the CSS pattern for rewriting url(foo) because the regex patterns are case-insensitive.

This also applies to the previous CachedFilesMixin from before 1.7.

Please let me know if a fix for this would be accepted, and I'll put together a test case and patch.

[aehlke]

I'm preparing a test case and patch.

[aehlke]

I've submitted a pull request with test coverage (a test which fails before applying the patch) and patch for the fix. Please let me know if anything needs changing.

[aehlke]

This patterns property is also documented in the Django docs, which I think adds priority to getting this fixed as it makes it sound like something you can extend (where in current versions you cannot actually extend without subtly broken behavior.)

[Tim Graham]

A ticket shouldn't be closed until the fix is committed to Django.

[aehlke]

timo: Ah ok, sorry about that. Thanks.

[Tim Graham]

I left comments for improvement on the PR. Please uncheck "Patch needs improvement" when you update it, thanks.

[James Aylett]

Is this the same as #19670?

[Claude Paroz]

Replying to jaylett:

Is this the same as #19670?

I think so.