Easy to use i18n library for Python
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i18n Fix tests Oct 22, 2018


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This library provides i18n functionality for Python 3 out of the box. The usage is mostly based on Rails i18n library.


Just run

pip install python-i18n

If you want to use YAML to store your translations, use

pip install python-i18n[YAML]


Basic usage

The simplest, though not very useful usage would be

import i18n
i18n.add_translation('foo', 'bar')
i18n.t('foo') # bar

Using translation files

YAML and JSON formats are supported to store translations. With the default configuration, if you have the following foo.en.yml file

  hi: Hello world !

in /path/to/translations folder, you simply need to add the folder to the translations path.

import i18n
i18n.t('foo.hi') # Hello world !

Please note that YAML format is used as default file format if you have yaml module installed. If both yaml and json modules available and you want to use JSON to store translations, explicitly specify that: i18n.set('file_format', 'json')


File namespaces

In the above example, the translation key is foo.hi and not just hi. This is because the translation filename format is by default {namespace}.{locale}.{format}, so the {namespace} part of the file is used as translation.

To remove {namespace} from filename format please change the filename_format configuration.

i18n.set('filename_format', '{locale}.{format}')

Directory namespaces

If your files are in subfolders, the foldernames are also used as namespaces, so for example if your translation root path is /path/to/translations and you have the file /path/to/translations/my/app/name/foo.en.yml, the translation namespace for the file will be my.app.name and the file keys will therefore be accessible from my.app.name.foo.my_key.



You can of course use placeholders in your translations. With the default configuration, the placeholders are used by inserting %{placeholder_name} in the ntranslation string. Here is a sample usage.

i18n.add_translation('hi', 'Hello %{name} !')
i18n.t('hi', name='Bob') # Hello Bob !


Pluralization is based on Rail i18n module. By passing a count variable to your translation, it will be pluralized. The translation value should be a dictionnary with at least the keys one and many. You can add a zero or few key when needed, if it is not present many will be used instead. Here is a sample usage.

i18n.add_translation('mail_number', {
    'zero': 'You do not have any mail.',
    'one': 'You have a new mail.',
    'few': 'You only have %{count} mails.',
    'many': 'You have %{count} new mails.'
i18n.t('mail_number', count=0) # You do not have any mail.
i18n.t('mail_number', count=1) # You have a new mail.
i18n.t('mail_number', count=3) # You only have 3 new mails.
i18n.t('mail_number', count=12) # You have 12 new mails.


You can set a fallback which will be used when the key is not found in the default locale.

i18n.set('locale', 'jp')
i18n.set('fallback', 'en')
i18n.add_translation('foo', 'bar', locale='en')
i18n.t('foo') # bar

Skip locale from root

Sometimes i18n structure file came from another project or not contains root element with locale eg. en name.

    "foo": "FooBar"

However we would like to use this i18n .json file in our Python sub-project or micro service as base file for translations. python-i18n has special configuration tha is skipping locale eg. en root data element from the file.

i18n.set('skip_locale_root_data', True)