#35417: RequestContext.new creates a context that cannot be flattened
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Reporter: Lily Foote | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 5.0
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Lily Foote:
Old description:
> In
> [https://github.com/django/django/blob/c187f5f9242b681abaa199173e02066997439425/django/template/library.py#L273
> InclusionNode.render] Django creates a {{{new_context}}} from two
> existing contexts ({{{context}}} and {{{_dict}}}) by calling
> {{{new_context = context.new(_dict)}}}. These can both be instances of
> {{{RequestContext}}} leading to {{{new_context}}} also being a
> {{{RequestContext}}} (I have not tried with any other context types).
> However, calling {{{new_context.flatten()}}} raises a {{{ValueError}}}:
>
> {{{
> ValueError: dictionary update sequence element #0 has length 1; 2 is
> required
> }}}
>
> I can reproduce this in a small test:
>
> {{{
> from django.template.context import RequestContext
> from django.test import RequestFactory, TestCase
>
> class RequestContextTestCase(TestCase):
> def test_flatten_request_context_new(self):
> factory = RequestFactory()
>
> request = factory.get("/foo/")
> context = RequestContext(request)
> context_2 = RequestContext(request)
> context_3 = context.new(context_2)
>
> self.assertEqual(
> context_3.flatten(), {"False": False, "None": None, "True":
> True}
> )
> }}}
>
> I discovered this when running Kolo on a Django admin view
> (http://127.0.0.1:8000/admin/auth/user/). Kolo calls
> {{{context.flatten()}}} internally when introspecting a template during
> rendering, which leads to this exception:
>
> {{{
> Traceback (most recent call last):
> File
> "/home/lily/work/kloppindustries/kolo/python/src/kolo/profiler.py", line
> 170, in __call__
> frame_data = processor.process(
> ^^^^^^^^^^^^^^^^^^
> File "/home/lily/work/kloppindustries/kolo/python/src/kolo/plugins.py",
> line 107, in process
> data.update(self.process_extra(frame, event, arg, self.context))
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> File
> "/home/lily/work/kloppindustries/kolo/python/src/kolo/filters/django.py",
> line 89, in process_django_template
> template_context = template_context.flatten()
> ^^^^^^^^^^^^^^^^^^^^^^^^^^
> File "/home/lily/.local/share/lilyenv/virtualenvs/kolo-
> sandbox/3.12/lib/python3.12/site-packages/django/template/context.py",
> line 120, in flatten
> flat.update(d)
> ValueError: dictionary update sequence element #0 has length 3; 2 is
> required
> }}}
New description:
In
[https://github.com/django/django/blob/c187f5f9242b681abaa199173e02066997439425/django/template/library.py#L273
InclusionNode.render] Django creates a {{{new_context}}} from two existing
contexts ({{{context}}} and {{{_dict}}}) by calling {{{new_context =
context.new(_dict)}}}. These can both be instances of {{{RequestContext}}}
leading to {{{new_context}}} also being a {{{RequestContext}}} (I have not
tried with any other context types). However, calling
{{{new_context.flatten()}}} raises a {{{ValueError}}}:
{{{
ValueError: dictionary update sequence element #0 has length 1; 2 is
required
}}}
I can reproduce this in a small test:
{{{
from django.template.context import RequestContext
from django.test import RequestFactory, TestCase
class RequestContextTestCase(TestCase):
def test_flatten_request_context_new(self):
factory = RequestFactory()
request = factory.get("/foo/")
context = RequestContext(request)
context_2 = RequestContext(request)
context_3 = context.new(context_2)
self.assertEqual(
context_3.flatten(), {"False": False, "None": None, "True":
True}
)
}}}
I discovered this when running Kolo on a Django admin view
(http://127.0.0.1:8000/admin/auth/user/). Kolo calls
{{{context.flatten()}}} internally when introspecting a template during
rendering, which leads to this exception:
{{{
Traceback (most recent call last):
File "/home/lily/work/kloppindustries/kolo/python/src/kolo/profiler.py",
line 170, in __call__
frame_data = processor.process(
^^^^^^^^^^^^^^^^^^
File "/home/lily/work/kloppindustries/kolo/python/src/kolo/plugins.py",
line 107, in process
data.update(self.process_extra(frame, event, arg, self.context))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File
"/home/lily/work/kloppindustries/kolo/python/src/kolo/filters/django.py",
line 89, in process_django_template
template_context = template_context.flatten()
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/lily/.local/share/lilyenv/virtualenvs/kolo-
sandbox/3.12/lib/python3.12/site-packages/django/template/context.py",
line 120, in flatten
flat.update(d)
ValueError: dictionary update sequence element #0 has length 3; 2 is
required
}}}
This is similar to #24765 and #26041.
--
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Ticket URL: <https://code.djangoproject.com/ticket/35417#comment:1>
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