Internationalizating of strings in extensions

See also

In order to internationalize you extension you must mark the strings for internationalization. You can find out how to do this by reading :doc: /contributing/frontend/string-i18n.rst

See also

In this tutorial we are assuming that you have read the :doc: /extensions/tutorial

We will create a simple extension that demonstrates the translation of strings inside extensions. After running

paster –plugin=ckan create -t ckanext ckanext-itranslation

Change and simply the plugin.py file to be

from ckan import plugins
from ckan.plugins import toolkit


class ExampleITranslationPlugin(plugins.SingletonPlugin):
    plugins.implements(plugins.IConfigurer)

    def update_config(self, config):
        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 just provides a sample string that we will be internationalizing in this tutorial.

Extracting 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 these them. If you have your templates in a directory differing from the default location, you may need to change the message_extractors stanza, you can read more about message extractors at the babel documentation

Add an directory to store your translations

mkdir ckanext-itranslations/i18n

Next you will need a babel config file. Add setup.cfg file containing

[extract_messages]
keywords = translate isPlural
add_comments = TRANSLATORS:
output_file = i18n/ckanext-itranslation.pot
width = 80

[init_catalog]
domain = ckanext-itranslation
input_file = i18n/ckanext-itranslation.pot
output_dir = i18n

[update_catalog]
domain = ckanext-itranslation
input_file = i18n/ckanext-itranslation.pot
output_dir = i18n
previous = true

[compile_catalog]
domain = ckanext-itranslation
directory = 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 an manage your translations using transifex or manually create your translations.

Creating translations manually

We will be creating 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. Edit this file to contain the following.

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 them command line client

Compiling the catalog

Now compile the PO files by running

python setup.py compile_catalog -l fr

This will generate an mo file containing your translations.

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.

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):
        toolkit.add_template_directory(config, 'templates')

Your done! To test your translated extension, make sure you add the extension to your /etc/ckan/default/development.ini and run a paster serve and browse to http://localhost:5000. You should find that switching to the fr locale in the web interface should 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 having your plugin not inherit from the DefaultTranslation class and implement the ITranslation interface yourself.

i18n_directory() Change the directory of the .mo translation files
i18n_locales() Change the list of locales that this plugin handles
i18n_domain() Change the gettext domain handled by this plugin