MediaAsset instances with attributes should not compare equal to strings

[Milad Khoshdel]

After the fix for #37088, MediaAsset.__eq__() still considers an asset equal to a string containing the same path, while MediaAsset.__hash__() includes the asset's attributes.

This violates Python's requirement that equal objects have equal hashes.

Reproduction on Django 6.2.dev20260831204047:

from django.forms import Script

asset = Script("/static/app.js", defer=True)
path = "/static/app.js"

print(asset == path)
print(hash(asset) == hash(path))
print(path in {asset})

Output:

True
False
False

Although asset == path, a set cannot find path because the two objects are placed in different hash buckets. Dictionary lookups can be affected in the same way. Stylesheet instances with attributes have the same issue.

Expected behavior: Whenever asset == path, hash(asset) == hash(path).

This appears to be a regression introduced by bc9bed573ce39c3b739a4a3b7848816d464b6bdc for #37088 in Django 6.1.

A possible fix is to hash only self._path. Assets with the same path but different attributes may then share a hash while remaining unequal, which is valid Python behavior.

[Milad Khoshdel]

I have a patch and regression test ready for this issue. PR #21866 ​https://github.com/django/django/pull/21866 was automatically closed because the ticket is still Unreviewed. I am continuing to work on the ticket and will reopen or update the PR once the ticket is accepted.

[Jacob Walls]

Thanks, I agree this this doesn't look right. We don't seem to be checking attributes when other is str, e.g.

from django.forms import Script, Stylesheet
asset = Stylesheet("/static/app.js")
asset2 = "/static/app.js"
assert asset == asset2  # works (shouldn't)
asset3 = Script("/static/app.js")
assert asset == asset3  # fails only here

That would lead me to expect a solution like:

django/forms/widgets.py

@@ -78 +78 @@
             self.__class__ is other.__class__
             and self._path == other._path
             and self.attributes == other.attributes
-        ) or (isinstance(other, str) and self._path == other)
+        ) or (isinstance(other, str) and not self.attributes and self._path == other)
 
     def __hash__(self):
         # Compare path and attrs to ensure performant comparison

Which gives test failures like:

======================================================================
FAIL: test_add_empty (forms_tests.tests.test_media.FormsMediaTestCase.test_add_empty)
----------------------------------------------------------------------
Traceback (most recent call last):
...
    ^^^^^^^^^^^^^^^
AssertionError: Lists differ: [{'screen': [Stylesheet('a.css')]}] != [{'screen': ['a.css']}]

First differing element 0:
{'screen': [Stylesheet('a.css')]}
{'screen': ['a.css']}

- [{'screen': [Stylesheet('a.css')]}]
?              -----------       -

+ [{'screen': ['a.css']}]

... but if there is no functional impact to that change, then can we just update the assertions?

[Milad Khoshdel]

Thanks, that makes sense. The failing assertions currently rely on this comparison:

Stylesheet("a.css", media="screen") == "a.css"

This is currently True, even though _css_lists contains a Stylesheet instance rather than a string. With the proposed change, it becomes False, so the expected value should use the normalized object:

{"screen": [Stylesheet("a.css", media="screen")]}

The functional change is the intended one: assets with attributes no longer compare equal to plain strings. Regular media merging and rendering remain unchanged because ordinary string paths are normalized into Script or Stylesheet instances before merging.

After updating these assertions, the full Forms test suite passes. I’ll revise the patch accordingly and reopen the PR.

[Milad Khoshdel]

A patch is available at ​PR.

It prevents MediaAsset instances with attributes from comparing equal to strings and updates the affected tests to use normalized Stylesheet instances.

[Sarah Boyce]

Confirmed that this also doesn't work in 5.2 and 6.0, so is not a regression introduced in 6.1