Genshi Tutorial: Adding Internationalization

To internationalize our application we'll use ​Babel.

easy_install Babel

To get the basic info on how to work with message catalog using Babel ​read this, I'll just follow you through the basic procedures.

First we'll create a locale directory under geddit which will hold the message catalogs. Next, we'll create a mapping file which will tell Babel how to handle the several type of files. Create a mappings.cfg on the directory above the geddit one and add inside:

# Extraction from Python source files

[python: **.py]

# Extraction from Genshi HTML and text templates

[genshi: **/templates/**.html]

The above will tell Babel that .py files should be handled by the python extractor and that the .html files should be handled by the Genshi extractor.

Now let's extract some messages to be translated:

pybabel extract -o geddit/locale/geddit.pot -F ./mappings.cfg geddit

The output should be similar to:

extracting messages from geddit/__init__.py
extracting messages from geddit/controller.py
extracting messages from geddit/form.py
extracting messages from geddit/model.py
extracting messages from geddit/translator.py
extracting messages from geddit/lib/__init__.py
extracting messages from geddit/lib/ajax.py
extracting messages from geddit/lib/template.py
extracting messages from geddit/templates/_comment.html
extracting messages from geddit/templates/_form.html
extracting messages from geddit/templates/comment.html
extracting messages from geddit/templates/index.html
extracting messages from geddit/templates/info.html
extracting messages from geddit/templates/layout.html
extracting messages from geddit/templates/submit.html
writing PO template file to geddit/locale/geddit.pot

Now let's create the English catalog which normally isn't translated:

pybabel init -D geddit -i geddit/locale/geddit.pot -d geddit/locale/ -l en

And, since I'm Portuguese, we'll create a Portuguese catalog to serve as an example:

pybabel init -D geddit -i geddit/locale/geddit.pot -d geddit/locale/ -l pt_PT

On this step you can create a catalog in your mother language if not english so that you can see Geddit translated.

Edit the contents of the resulting geddit.po for the locale you created, translate it, save and exit.

Next step will involve compiling these catalogs so that they can be used by python's gettext module:

pybabel compile -D geddit -d geddit/locale/ -f --statistics

Now, our Geddit application needs to use and know how to use these translated catalogs.

Let's modify geddit/controller.py with(this is a diff):

geddit/controller.py

@@ -92 +92 @@
             links = sorted(self.data.values(), key=operator.attrgetter('time'))
             return template.render(links=links)
 
+    @cherrypy.expose
+    def set_lang(self, language):
+       import gettext
+       import formencode
+       import __builtin__
+       locale_dir = os.path.join(os.path.dirname(__file__), 'locale')
+       domain = 'geddit'
+       codeset= 'utf-8'
+
+       gettext.bindtextdomain(domain, locale_dir)
+       gettext.textdomain(domain)
+
+       try:
+            translator = gettext.translation(domain,
+                                         locale_dir,
+                                         languages=[language],
+                                         codeset=codeset)
+       except IOError, error:
+            language=['en']
+            translator = gettext.translation(domain,
+                                         locale_dir,
+                                         languages=language,
+                                         codeset=codeset)
+       formencode.api.set_stdtranslation(languages=[language])
+       __builtin__._ = translator.ugettext
+       raise cherrypy.HTTPRedirect('/')
+
+
 
 def main(filename):
+    import __builtin__
+    from gettext import NullTranslations
+
+    __builtin__._ = NullTranslations().ugettext
     # load data from the pickle file, or initialize it to an empty list
     if os.path.exists(filename):
         fileobj = open(filename, 'rb')

Our geddit/lib/template.py with(also diff):

geddit/lib/template.py

@@ -4 +4 @@
 from genshi.core import Stream
 from genshi.output import encode, get_serializer
 from genshi.template import Context, TemplateLoader
+from genshi.filters import Translator
 
 from geddit.lib import ajax
 
@@ -42 +43 @@
         template = loader.load(args[0])
     else:
         template = cherrypy.thread_data.template
+    template.filters.insert(0, Translator(_))
     ctxt = Context(url=cherrypy.url)
     ctxt.push(kwargs)
     return template.generate(ctxt)

WARNING: there's an error in the above code, please see #238.

And finaly our geddit/templates/layout.html with(also diff):

geddit/templates/layout.html

@@ -19 +19 @@
         <a href="/"><img src="${url('/media/logo.gif')}" width="201" height="79" alt="geddit?" /></a>
       </div>
       <div id="content">
+        <form method="post" id="lang_choose" name="lang_choose" action="${url('/set_lang')}">
+        <label for="language">Language:</label>
+        <select id="language" name="language" onChange="$('#lang_choose').submit()">
+          <option value="en">English</option>
+          <option value="pt_PT">Portuguese</option>
+        </select>
+        </form>
+        <noscript>
+          <input type="submit" name="submit" value="Update"/>
+        </noscript>
         ${select('*|text()')}
       </div>
       <div id="footer">

This will allow the user to select the language.

And that wraps it up!