Cache tag doesn't handle filter expresssions

[FunkyBob]

I found the cache tag didn't well handle when I passed, for instance:

{% cache ..... request.GET.foo %}

As it would raise an exception if GETfoo wasn't set... so I tried passing a default:

{% cache ..... request.GET.foo|default:"bar" %}

Only to see it not only didn't fix the issue, but didn't appear to be parsing filter expressions, either.

I've updated the cache tag to use parser.compile_filter for all its arguments.

[FunkyBob]

Changed to using token.split_contents() instead of token.contents.split() [thanks, brad!]

[FunkyBob]

Fixed error message

[Bradley Ayers]

Looks good to me. Nice job FunkyBob

[Simon Charette]

IMHO this should be tested.

[wkeeling]

I was looking through the easy pickings and thought I'd write a regression test for this one. Whilst working on the test I discovered that because the cache tag now does parser.compile_filter for all its arguments, it was converting the fragment name into a filter expression. This caused the cache tag to treat the fragment name as a variable and attempt to look it up in its context. The lookup would return nothing, and so the resulting cache key would be missing the fragment name. This would then cause the wrong fragments to be returned from the cache in certain cases.

I've attached a new patch (which doesn't treat the fragment name as a filter expression) plus the regression tests.

[Simon Charette]

You can drop the u':' at line 27 since your using module wide unicode literals: from __future__ import unicode_literals.

Maybe we should add a release note for that? All tests pass on Python 2.7.3rc1 sqlite3.

[Simon Charette]

Removed trailing whitespace and a unicode literal

[Baptiste Mispelon]

I "accidentally" fixed this while working on a different bug.

I have a pull request for this and #6271 at ​https://github.com/django/django/pull/751

[Baptiste Mispelon <bmispelon@…>]

In 069280a6893d0f496c8f15922807939c68459ec3:

Used token.split_contents() for tokenisation in template tags accepting variables.

Fixed #6271, #18260.