ability to change language via url redirect, added docstring

[needlestack]

Summary

(resubmitting against develop branch per request)

In multi-lingual environments, it is not user friendly for each user to change the default language manually with the drop-down box on the bottom of the page. This patch allows setting the language through a link, which then redirects the user to the requested content. We use this patch in RACHEL for our multi-lingual installations. You can see it in action here, where we link to English, French, and Spanish versions on the same server:

http://rachelfriends.org/previews/rachelplus-en/
http://rachelfriends.org/previews/rachelplus-es/
http://rachelfriends.org/previews/rachelplus-fr/

It would be nice if this functionality were included in the official release.

TODO

• No tests existed for this module - I don't know how to write tests for python/django
• I have added documentation (there was none before)
• New dependencies in this file: from django.shortcuts import redirect

[benjaoming]

This looks good, except we now have a new test failure :) This is reported in Circle CI...

======================================================================
FAIL: test_responses (kalite.distributed.tests.url_tests.AllUrlsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/ubuntu/ka-lite/kalite/distributed/tests/url_tests.py", line 138, in test_responses
    check_urls(module.urlpatterns)
  File "/home/ubuntu/ka-lite/kalite/distributed/tests/url_tests.py", line 95, in check_urls
    check_urls(pattern.url_patterns, prefix=new_prefix)
  File "/home/ubuntu/ka-lite/kalite/distributed/tests/url_tests.py", line 95, in check_urls
    check_urls(pattern.url_patterns, prefix=new_prefix)
  File "/home/ubuntu/ka-lite/kalite/distributed/tests/url_tests.py", line 127, in check_urls
    url=url, status_code=response.status_code))
AssertionError: 500 not found in [200, 302, 400, 401, 404, 405] : /api/i18n/set_default_language/ gave status code 500

I believe the test may be caused by calling the page by GET without the lang param set. You should probably just fail gracefully or return a 302 redirect?

You can run the failing test like this: bin/kalite manage test distributed.AllUrlsTest

[codecov-io]

Current coverage is 51.22% (diff: 4.00%)

Merging #5342 into develop will increase coverage by 0.03%

@@            develop      #5342   diff @@
==========================================
  Files           141        141          
  Lines          7447       7458    +11   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits           3812       3820     +8   
- Misses         3635       3638     +3   
  Partials          0          0          

Powered by Codecov. Last update 5d5928f...9e2957b

[needlestack]

Ah, good idea. I have made this change and committed to this branch.

One problem, though -- I tested this change manually, but I was not able to run the test code as directed. When trying against my branch, I got "ImportError: No module named kalite" and when I tried under the master branch I got "ImportError: No module named dbbackup". Sorry, I'm not familiar enough with python and django :/

I guess we'll see if the automatic CircleCI tests turn anything up. Thanks for your help so far!

[needlestack]

Not sure what that codecov/patch error means - any suggestions appreciated...

[benjaoming]

@needlestack thanks that's great!! I would think that now we have the tests working, then it's safe to merge. Judging from the previous fail then the tests do reach part of the function.

codecov/patch is the metric for the code that's affected - I think it means that tests has only reached 4% of the changed lines.

Overall, it stacks up, but it means that you have contributed code where I have to rely on your assertion that it's working and my own ability to read code :)

But it's all good! I will write something for the release notes and possibly add a quick remark to ensure that future devs are able to understand why this code is there.

[needlestack]

Great - thanks for your help. Hope others find this useful!