Internationalizing strings in extensions
See also
In order to internationalize your extension you must mark its strings for internationalization. See also Translating CKAN.
This tutorial assumes that you have read the Writing extensions tutorial.
We will create a simple extension to demonstrate the translation of strings inside extensions. After running:
ckan -c |ckan.ini| create -t ckanext ckanext-itranslation
Change the plugin.py
file to:
# encoding: utf-8
from ckan.common import CKANConfig
from ckan import plugins
from ckan.plugins import toolkit
class ExampleITranslationPlugin(plugins.SingletonPlugin):
plugins.implements(plugins.IConfigurer)
def update_config(self, config: CKANConfig):
toolkit.add_template_directory(config, 'templates')
Add a template file ckanext-itranslation/templates/home/index.html
containing:
{% ckan_extends %}
{% block primary_content %}
{% trans %}This is an untranslated string{% endtrans %}
{% endblock %}
This template provides a sample string that we will internationalize in this tutorial.
Note
While this tutorial only covers Python/Jinja templates it is also possible (since CKAN 2.7) to translate strings in an extension’s JavaScript modules.
Extract strings
Tip
If you have generated a new extension whilst following this tutorial the
default template will have generated these files for you and you can simply
run the extract_messages
command immediately.
Check your setup.py
file in your extension for the following lines
setup(
entry_points='''
[ckan.plugins]
itranslation=ckanext.itranslation.plugin:ExampleITranslationPlugin
[babel.extractors]
ckan = ckan.lib.extract:extract_ckan
'''
message_extractors={
'ckanext': [
('**.py', 'python', None),
('**.js', 'javascript', None),
('**/templates/**.html', 'ckan', None),
],
}
These lines will already be present in our example, but if you are adding
internationalization to an older extension, you may need to add them.
If you have your templates in a directory differing from the default location
(ckanext/yourplugin/i18n
),
you may need to change the message_extractors
stanza. You can read more
about message extractors in the babel documentation.
Add a directory to store your translations:
mkdir ckanext-itranslations/ckanext/itranslations/i18n
Next you will need a babel config file. Add a setup.cfg
file containing the
following (make sure you replace itranslations
with the name of your extension):
[extract_messages]
keywords = translate isPlural
add_comments = TRANSLATORS:
output_file = ckanext/itranslation/i18n/ckanext-itranslation.pot
width = 80
[init_catalog]
domain = ckanext-itranslation
input_file = ckanext/itranslation/i18n/ckanext-itranslation.pot
output_dir = ckanext/itranslation/i18n
[update_catalog]
domain = ckanext-itranslation
input_file = ckanext/itranslation/i18n/ckanext-itranslation.pot
output_dir = ckanext/itranslation/i18n
[compile_catalog]
domain = ckanext-itranslation
directory = ckanext/itranslation/i18n
statistics = true
This file tells babel where the translation files are stored.
You can then run the extract_messages
command to extract the strings from
your extension:
python setup.py extract_messages
This will create a template PO file named
ckanext/itranslations/i18n/ckanext-itranslation.pot
.
At this point, you can either upload and manage your translations using Transifex or manually edit your translations.
Manually create translations
We will create translation files for the fr
locale. Create the translation
PO files for the locale that you are translating for by running init_catalog:
python setup.py init_catalog -l fr
This will generate a file called i18n/fr/LC_MESSAGES/ckanext-itranslation.po
.
This file should contain the untranslated string on our template. You can manually add
a translation for it by editing the msgstr
section:
msgid "This is an untranslated string"
msgstr "This is a itranslated string"
Translations with Transifex
Once you have created your translations, you can manage them using Transifex. This is out side of the scope of this tutorial, but the Transifex documentation provides tutorials on how to upload translations and how to manage them using the command line client.
Compiling the catalog
Once the translation files (po
) have been updated, either manually or via Transifex, compile them
by running:
python setup.py compile_catalog
This will generate a mo
file containing your translations that can be used by CKAN.
The ITranslation interface
Once you have created the translated strings, you will need to inform CKAN that
your extension is translated by implementing the ITranslation
interface in
your extension. Edit your plugin.py
to contain the following.
# encoding: utf-8
from ckan.common import CKANConfig
from ckan import plugins
from ckan.plugins import toolkit
from ckan.lib.plugins import DefaultTranslation
class ExampleITranslationPlugin(plugins.SingletonPlugin, DefaultTranslation):
plugins.implements(plugins.ITranslation)
plugins.implements(plugins.IConfigurer)
def update_config(self, config: CKANConfig):
toolkit.add_template_directory(config, 'templates')
You’re done! To test your translated extension, make sure you add the extension to
your /etc/ckan/default/ckan.ini, run a ckan run
command and browse to
http://localhost:5000. You should find that switching to the fr
locale in
the web interface will change the home page string to this is an itranslated
string
.
Advanced ITranslation usage
If you are translating a CKAN extension that already exists, or you have
structured your extension differently from the default layout. You may have to
tell CKAN where to locate your translated files, you can do this by not having
your plugin inherit from the DefaultTranslation
class and instead
implement the ITranslation
interface yourself.
Change the directory of the .mo translation files |
|
Change the list of locales that this plugin handles |
|
Change the gettext domain handled by this plugin |