tag "trans" not working with "context"

[lanyjie]

Hi I am using the "trans" tag to do context aware translation. In my template I had something like:

    {%trans "Budget" context "finance"%}

then as I "makemessages", the context does not appear in my django.po file. What's more, it fails to translate properly even if I had provided the correct translation in the django.po file and compiled the messages.

[lanyjie]

I also used pgettext("context", "message") in my code, and it didn't work either. Note the context was given in Chinese.

[Claude Paroz]

I'm not able to reproduce your problem. Maybe you can give us your real file so we can test?

[lanyjie]

Maybe it is my mistake -- I can't reproduce it anymore. When I played with it, I found something highly related: if you use both double quote and single quote, the single quote version won't show up with context. Here is what I mean:

    {%trans "Budget" context "finance"%}

Then somewhere else you have:

    {%trans 'Budget' context 'finance'%}

Seems the translation system treats them as two different entries.

[Julien Phalip]

For the record, a while ago a similar ticket was created: #18114. But I couldn't reproduce the problem either for that one either.

That seems unlikely, but perhaps there's an issue with this tag handling single quotes.

Could you try writing a unit test showing the problem?

[lanyjie]

I would love to try write a unit test if someone can give me an example for the i18n module. For now, I can specify how to reproduce this problem:

1. in a django project, write a real simple template file named "testempt.html" with two lines like this:

       {%trans "budget" context "finance"%}
   
       "{%trans 'budget' context 'finance'%}"
   

2. now issue this command:

       python manage.py makemessages -l en
   

3. then open the message file django.po and you will get this:

   #: testempt.html:1
   msgctxt "finance"
   msgid "budget"
   msgstr ""
   
   #: testempt.html:3
   msgid "budget"
   msgstr ""
   

[Julien Phalip]

Thanks for the code snippet. If you'd like to have a go at writing a unit test, you can take a look at the existing tests in ​https://github.com/django/django/blob/master/tests/regressiontests/i18n/commands/extraction.py

[lanyjie]

@julien: I looked at that code and it seems we can do the following with the testempt.html:

    def test_template_message_context_extractor(self):
        """
        Ensure that message contexts are correctly extracted for the
        {% trans %} and {% blocktrans %} template tags.
        Refs #14806.
        """
        os.chdir(self.test_dir)
        management.call_command('makemessages', locale=LOCALE, verbosity=0)
        self.assertTrue(os.path.exists(self.PO_FILE))
        with open(self.PO_FILE, 'r') as fp:
            po_contents = fp.read()
            # {% trans %}
            self.assertTrue('msgctxt "Special trans context #1"' in po_contents)
            self.assertTrue("Translatable literal #7a" in po_contents)
            self.assertTrue('msgctxt "Special trans context #2"' in po_contents)
            self.assertTrue("Translatable literal #7b" in po_contents)
            self.assertTrue('msgctxt "Special trans context #3"' in po_contents)
            self.assertTrue("Translatable literal #7c" in po_contents)

            #ticket #18881, single quote context
            self.assertTrue('msgctxt "finance"' in po_contents)
            self.assertMsgId('budget', po_contents)

            #{% blocktrans %}

However, the call of

    self.assertMsgId('finance', po_contents)

currently does NOT check for duplicate message id in the po file, which is not quite adequate.
Therefore, in the same file, where assertMsgId is defined, we can use the following definition instead:

    def assertMsgId(self, msgid, s, use_quotes=True):
        q = '"'
        if use_quotes:
            msgid = '"%s"' % msgid
            q = "'"
        needle = 'msgid %s' % msgid
        msgid = re.escape(msgid)
        matches = len(re.findall('^msgid %s' % msgid, s, re.MULTILINE))
        return self.assertTrue( matches==1, 
            'Could not find %(q)s%(n)s%(q)s in generated PO file' % {'n':needle, 'q':q} if matches==0 else
            'Found more than one occurrences of %(q)s%(n)s%(q)s in generated PO file' % {'n':needle, 'q':q})

[Julien Phalip]

It looks like there's a bug with the context's regular expressions. Marking this ticket as a release blocker as this was a new feature in 1.4 and therefore it should be fixed in 1.4.X as well.

I wrote a patch (see attached). Could you please try it in your project and check that it fixes your problem?

[lanyjie]

Thanks for the patch. I tried to use it by cd to the django installation folder and do

    django> patch --dry-run -p2 < ~/Downloads/18881.trans-context-single-quotes.diff

but it complains about "can't find file to patch at input line 5". any ideas?

[Julien Phalip]

Which exact version of Django are you using? If it's a git clone, which revision is it at?

The error you got is because the first patch I submitted also contained the tests. I've re-submitted another patch with the code change only. Could you try again with that one instead?

[lanyjie]

patch succeeded, and problem fixed. many thanks!

[Julien Phalip <jphalip@…>]

In b8244c654c85034bd4209a93a7802eb306c32e2b:

Fixed #18881 -- Made the context option in {% trans %} and {% blocktrans %} accept literals wrapped in single quotes. Thanks to lanyjie for the report.

[Julien Phalip <jphalip@…>]

In cc0478606a1d3dd804bc005a78e616550d3d0d41:

[1.4.x] Fixed #18881 -- Made the context option in {% trans %} and {% blocktrans %} accept literals wrapped in single quotes. Thanks to lanyjie for the report.