id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
25875	Unicode error when converting a Q object to a string	Ben Kraft	Ben Kraft	"If you have a model whose `__str__` returns non-ASCII text, and you refer to that model in a `Q` object, attempting to `print` that `Q` object, or otherwise convert it to a string, will error.  This is a regression in Django 1.5, caused indirectly by [https://github.com/django/django/commit/3dd5d72 3dd5d72], and remains an issue in master; I believe it should only affect python 2 but I haven't actually checked.

The issue appears to be that `django.utils.tree.Node.__str__` inadvertently attempts to convert the string back to unicode.  In particular, since [https://github.com/django/django/commit/3dd5d72 3dd5d72], `self.connector` is a unicode string if `self` is a `Q` object.  This causes python to convert the string being formatted and all its formatting arguments to unicode.  Since this is done implicitly it uses the default encoding (ASCII), which fails.

Fixing this should be as simple as just explicitly doing `str(self.connector)` instead, although I haven't yet run the tests to see if that breaks anything else.  In any case, I'm happy to write a patch to do that later this week.  It's possible it would be better to instead define a `__unicode__` method and avoid the string-conversion entirely, I'm not sure, but this seems simpler.

Complete repro:
{{{
# in models.py
class Foo(models.Model):
    name = models.TextField()
    def __unicode__(self):
        return u'Foö'
    def __str__(self):
        return unicode(self).encode('utf-8')
    def __repr__(self):
        return str(self)

# in a shell
Q(baz=Foo(name=""baz"")) # raises UnicodeDecodeError
}}}

Note that the repro works as long as at least one of `__unicode__`, `__str__`, and `__repr__` is defined and returns non-ASCII text -- they don't need to all be explicitly defined."	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0