Warn about raw "%" in redirect_to strings.

[daonb <bennydaon@…>]

from my urls.py:

url(r'^password/change/done/$',
    django.views.generic.simple.redirect_to,
    {'url': '/toviva/myroom/?' + urlencode({'message': _('Password change successful')})})

When I access the url I get an error:

ValueError at /toviva/accounts/password/change/done/
unsupported format character 'D' (0x44) at index 25

printing the url parameters in redirect_to:

/toviva/myroom/?message=%D7%94%D7%A1%D7%99%D7%A1%D7%9E%D7%94+%D7%A9%D7%95%D7%A0%D7%AA%D7%94+%D7%91%D7%94%D7%A6%D7%9C%D7%97%D7%94

In redirect_to the line that fails is:

   return HttpResponsePermanentRedirect(url % kwargs)

I found another way to do it:

  url(r'^password/change/done/$',
    django.views.generic.simple.redirect_to,
    {'url': '/toviva/myroom/?message=%(message)s', 'message': urlquote_plus(_('Password change successful'))}),

Which works for me, but still - I'd be happy if someone can find a way to make redirect_to more robust.

[Philippe Raoult]

AFAIK urls aren't supposed to be in unicode. urlquote is the way to go.

[daonb <bennydaon@…>]

Seems like I wasn't clear enough, sorry. For the love of Django, I'll try once more:

According to urllib.qoute documentation: "Replace special characters in string using the "%xx" escape....Example: quote('/~connolly/') yields '/%7econnolly/'"

After urlquote you get an ascii string with "%xx" escape for every special or unicode character. Using the "%" operator on this string crashes because it has too many '%' characters, usually with unsupported format characters - such as 7 in the Python Library Reference example (redirect_to does it in "url % kwargs") .

Hope it makes sense, in any case I'm re-opening the ticket. Hope I'm not violating the protocol, just want to make sure someone reads this.

[James Bennett]

Have you read ​the Unicode documentation?

[daonb <bennydaon@…>]

adding a call to iri_to_uri in redirect_to

[daonb <bennydaon@…>]

6892v1 changes redirect_to so it can accept an IRI in the url parameter. To keep it backward compatible, the url parameter name can not be changed. The patch is based on Django's unicode documentation (thanks ubernostrum):

>>> iri_to_uri(u'/favorites/François/%s' % urlquote(u'Paris & Orléans'))
'/favorites/Fran%C3%A7ois/Paris%20%26%20Orl%C3%A9ans'

[Malcolm Tredinnick]

This patch doesn't look like it's fixing the right problem. The problem is this: the url parameter passed to redirect_to() can contain dictionary-based format strings to accept parameters from the URL. In the example in the example in the description, the reporter is also including %-encoded characters as part of the URL. So we need to tell the difference between to uses of "%":

url = "%(param)s %7D"

The first one requires a substitution and the second should be left alone when we are subtituting the kwargs (and hence that "%" should really be "%%" in the string).

I suspect this is really a documentation issue. We could try to automatically detect the context of "%" signs in the url string, but that sounds like solving the problem at the wrong level. People using redirect_to() need to remember that they are passing in a format string and so any stray % signs need to be doubled (escaped as "%%"). Something like

my_string.replace("%", "%%")

So a documentation patch will be welcomed, but the current patch here isn't fixing the problem, since it looks like it doesn't solve the original error as described.

[daonb <bennydaon@…>]

A documentation patch

[Aymeric Augustin]

Change UI/UX from NULL to False.

[Aymeric Augustin]

Change Easy pickings from NULL to False.

[Claude Paroz]

The documentation for the new class-based view RedirectView is now clear:
Because keyword interpolation is always done (even if no arguments are passed in), any "%" characters in the URL must be written as "%%" so that Python will convert them to a single percent sign on output.
​https://docs.djangoproject.com/en/dev/ref/class-based-views/#django.views.generic.base.RedirectView

As for the use-case of the OP, I think that a .replace('%', '%%') should be appended to the urlencode() call.