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diff --git a/docs/topics/internationalization.md b/docs/topics/internationalization.md new file mode 100644 index 00000000..3968e23d --- /dev/null +++ b/docs/topics/internationalization.md @@ -0,0 +1,113 @@ +# Internationalization + +> Supporting internationalization is not optional. It must be a core feature. +> +> — [Jannis Leidel, speaking at Django Under the Hood, 2015][cite]. + +REST framework ships with translatable error messages. You can make these appear in your language enabling [Django's standard translation mechanisms][django-translation]. + +Doing so will allow you to: + +* Select a language other than English as the default, using the standard `LANGUAGE_CODE` Django setting. +* Allow clients to choose a language themselves, using the `LocaleMiddleware` included with Django. A typical usage for API clients would be to include an `Accept-Language` request header. + +## Enabling internationalized APIs + +You can change the default language by using the standard Django `LANGUAGE_CODE` setting: + + LANGUAGE_CODE = "es-es" + +You can turn on per-request language requests by adding `LocalMiddleware` to your `MIDDLEWARE_CLASSES` setting: + + MIDDLEWARE_CLASSES = [ + ... + 'django.middleware.locale.LocaleMiddleware' + ] + +When per-request internationalization is enabled, client requests will respect the `Accept-Language` header where possible. For example, let's make a request for an unsupported media type: + +**Request** + + GET /api/users HTTP/1.1 + Accept: application/xml + Accept-Language: es-es + Host: example.org + +**Response** + + HTTP/1.0 406 NOT ACCEPTABLE + + {"detail": "No se ha podido satisfacer la solicitud de cabecera de Accept."} + +REST framework includes these built-in translations both for standard exception cases, and for serializer validation errors. + +Note that the translations only apply to the error strings themselves. The format of error messages, and the keys of field names will remain the same. An example `400 Bad Request` response body might look like this: + + {"detail": {"username": ["Esse campo deve ser unico."]}} + +If you want to use different string for parts of the response such as `detail` and `non_field_errors` then you can modify this behavior by using a [custom exception handler][custom-exception-handler]. + +#### Specifying the set of supported languages. + +By default all available languages will be supported. + +If you only wish to support a subset of the available languages, use Django's standard `LANGUAGES` setting: + + LANGUAGES = [ + ('de', _('German')), + ('en', _('English')), + ] + +## Adding new translations + +REST framework translations are managed online using [Transifex][transifex-project]. You can use the Transifex service to add new translation languages. The maintenance team will then ensure that these translation strings are included in the REST framework package. + +Sometimes you may need to add translation strings to your project locally. You may need to do this if: + +* You want to use REST Framework in a language which has not been translated yet on Transifex. +* Your project includes custom error messages, which are not part of REST framework's default translation strings. + +#### Translating a new language locally + +This guide assumes you are already familiar with how to translate a Django app. If you're not, start by reading [Django's translation docs][django-translation]. + +If you're translating a new language you'll need to translate the existing REST framework error messages: + +1. Make a new folder where you want to store the internationalization resources. Add this path to your [`LOCALE_PATHS`][django-locale-paths] setting. + +2. Now create a subfolder for the language you want to translate. The folder should be named using [locale name][django-locale-name] notation. For example: `de`, `pt_BR`, `es_AR`. + +3. Now copy the [base translations file][django-po-source] from the REST framework source code into your translations folder. + +4. Edit the `django.po` file you've just copied, translating all the error messages. + +5. Run `manage.py compilemessages -l pt_BR` to make the translations +available for Django to use. You should see a message like `processing file django.po in <...>/locale/pt_BR/LC_MESSAGES`. + +6. Restart your development server to see the changes take effect. + +If you're only translating custom error messages that exist inside your project codebase you don't need to copy the REST framework source `django.po` file into a `LOCALE_PATHS` folder, and can instead simply run Django's standard `makemessages` process. + +## How the language is determined + +If you want to allow per-request language preferences you'll need to include `django.middleware.locale.LocaleMiddleware` in your `MIDDLEWARE_CLASSES` setting. + +You can find more information on how the language preference is determined in the [Django documentation][django-language-preference]. For reference, the method is: + +1. First, it looks for the language prefix in the requested URL. +2. Failing that, it looks for the `LANGUAGE_SESSION_KEY` key in the current user’s session. +3. Failing that, it looks for a cookie. +4. Failing that, it looks at the `Accept-Language` HTTP header. +5. Failing that, it uses the global `LANGUAGE_CODE` setting. + +For API clients the most appropriate of these will typically be to use the `Accept-Language` header; Sessions and cookies will not be available unless using session authentication, and generally better practice to prefer an `Accept-Language` header for API clients rather than using language URL prefixes. + +[cite]: http://youtu.be/Wa0VfS2q94Y +[django-translation]: https://docs.djangoproject.com/en/1.7/topics/i18n/translation +[custom-exception-handler]: ../api-guide/exceptions.md#custom-exception-handling
+[transifex-project]: https://www.transifex.com/projects/p/django-rest-framework/ +[django-po-source]: https://raw.githubusercontent.com/tomchristie/django-rest-framework/master/rest_framework/locale/en_US/LC_MESSAGES/django.po +[django-language-preference]: https://docs.djangoproject.com/en/1.7/topics/i18n/translation/#how-django-discovers-language-preference +[django-locale-paths]: https://docs.djangoproject.com/en/1.7/ref/settings/#std:setting-LOCALE_PATHS +[django-locale-name]: https://docs.djangoproject.com/en/1.7/topics/i18n/#term-locale-name +[contributing]: ../../CONTRIBUTING.md |