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Don't leave `compressed` in the render context #354

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The compress template tag should push/pop the context when rendering so as to not overwrite a template variable called compressed.


I noticed this breaks the Jinja2 extension tests, because it uses dictionaries for the context, which have a different pop() method. I'm not sure how to proceed here.


Sorry, I'm closing this because Jinja2 compatibility is forcing our hand here. I don't want to add more complexity for such a small issue, so I don't think adding a workaround specifically for jinja2 would be a good idea.

@diox diox closed this

It should be documented that you're not allowed to use a template context variable called compressed when using django-compressor. Where's a good place to put this in the docs?


I guess somewhere in the usage section. Alternatively, it looks like we don't do a very good job at explaining the compressor templates & context so we could have a full section for it if you really want to go the extra mile and write that too :-p

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Showing with 14 additions and 4 deletions.
  1. +5 −2 compressor/templatetags/
  2. +9 −2 compressor/tests/
7 compressor/templatetags/
@@ -94,7 +94,7 @@ def render_compressed(self, context, kind, mode, forced=False):
not settings.COMPRESS_PRECOMPILERS) and not forced):
return self.get_original_content(context)
- context['compressed'] = {'name': getattr(self, 'name', None)}
+ context.update({'compressed': {'name': getattr(self, 'name', None)}})
compressor = self.get_compressor(context, kind)
# Prepare the actual compressor and check cache
@@ -107,13 +107,16 @@ def render_compressed(self, context, kind, mode, forced=False):
rendered_output = self.render_output(compressor, mode, forced=forced)
if cache_key:
cache_set(cache_key, rendered_output)
+ context.pop()
return rendered_output.decode('utf-8')
except Exception:
if settings.DEBUG or forced:
# Or don't do anything in production
- return self.get_original_content(context)
+ output = self.get_original_content(context)
+ context.pop()
+ return output
def render_output(self, compressor, mode, forced=False):
return compressor.output(mode, forced=forced)
11 compressor/tests/
@@ -2,6 +2,7 @@
import os
import sys
+import copy
from mock import Mock
@@ -121,14 +122,20 @@ def test_named_compress_tag(self):
{% endcompress %}
+ context_copy = []
def listener(sender, **kwargs):
- pass
+ context_copy.append(copy.deepcopy(kwargs['context']))
callback = Mock(wraps=listener)
args, kwargs = callback.call_args
context = kwargs['context']
- self.assertEqual('foo', context['compressed']['name'])
+ # compressed must be in the context while the tag is being rendered
+ self.assertEqual('foo', context_copy[0]['compressed']['name'])
+ # but it must not remain when the tag is done
+ self.assertRaises(KeyError, lambda: context['compressed'])
class PrecompilerTemplatetagTestCase(TestCase):
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