ValueError does not catch all cases when trying to determine type of variable in template.Variable class

[Tobias McNulty]

  File "/usr/lib/python2.5/site-packages/caktus/django/templatetags/__init__.py", line 59, in __init__
    self.kwargs = dict([(k, Variable(arg)) for k, arg in kwargs.items()])
  File "/usr/lib/python2.5/site-packages/django/template/__init__.py", line 628, in __init__
    self.literal = float(var)
TypeError: float() argument must be a string or a number

In my case "var" was a dict. obviously dict is not a supported variable type, so django should raise a more obvious error here.

[Malcolm Tredinnick]

It's not clear from the report what you are doing to trigger this error. Without knowing that, it's difficult to choose from amongst possible solutions.

[Tobias McNulty]

Sorry, here is how to reproduce it:

from django.template import Variable
Variable({})

[Matt McClanahan]

TypeError makes sense, just not on the float call. Patch to re-raise it with a more descriptive error.

[Alex Gaynor]

Marking as accepted, but this patch is wrong, Variable's constructor takes a basestring, and nothing else, we should just typecheck the input IMO.

[Yohann Gabory]

Just added a patch that raise if "var" is not a basestring.

[Baptiste Mispelon]

This patch is better, but to ensure python3 compatibility, you need to use six.string_types instead of basestring.

You also need to add some tests for this new feature (maybe in tests/template_tests/test_parser.py seeing as there's already some tests for Variable in there).

Thanks.

[Yohann Gabory]

use six.string_type instead of basestring for python3 compatibility. Added a test to check that a non string value raise a TypeError

[Steffen Zieger]

Fixes the test and improves code

[Yohann Gabory]

@saz : your attachment "type_check_test_working" is a copy'n'past of "type_check". For what purpose did you made ​​it ?

[Steffen Zieger]

Almost. Have a look at line 25 in your patch and lines 25 to 27 in my patch.

After applying your patch, running the tests has thrown an exception for me.
Changing the self.assertRaisses line as it is documented (​http://docs.python.org/2/library/unittest.html#unittest.TestCase.assertRaises) everything is working as expected.

[Tim Graham <timograham@…>]

In 7fec5a2240835af7c7f3accd64d9d894d4f92782:

Fixed #7557 -- Added type checking to Variable initialization.

Thanks tobias for the suggestion and boblefrag and saz for work on the
patch.