Translates Django model fields in a JSONField using a registration approach.

• Uses one django.contrib.postgres.JSONField (PostgreSQL jsonb field) for every record.
• Django 1.9, 1.10, 1.11 for now
• PostgreSQL >= 9.4 and Psycopg2 >= 2.5.4.

• Add 'modeltrans' your list of INSTALLED_APPS.
• Add a list of available languages to your settings.py: AVAILABLE_LANGUAGES = ('en', 'nl', 'de', 'fr')
• Add a translation.py in each app you want to translate models for.
• For each model you want to translate, create a TransltionOptions object and register the model using that object:

# models.py
from django.db import models


class Blog(models.Model):
    title = models.CharField(max_length=255)
    body = models.TextField(null=True)

# translation.py
from modeltrans.translator import TranslationOptions, translator

from .models import Blog, Category


class BlogTranslationOptions(TranslationOptions):
    fields = ('title', 'body')

translator.register(Blog, BlogTranslationOptions)

• Run ./manage.py makemigrations to add the i18n JSONField to each model containing translations.
• Each method now has some extra virtual fields. In the example above:
  • title_nl, title_de, ... allow getting/setting the specific languages
  • title_i18n follows the currently active translation in Django, and falls back to the default language:

>>> b = Blog.objects.create(title='Falcon', title_nl='Valk')
>>> b.title
'Falcon'
>>> b.title_nl
'Valk'
>>> b.title_i18n
'Falcon'
>>> from django.utils.translation import override
>>> with override('nl'):
...   b.title_i18n
...
'Valk'
# translations are stored in the field `i18n` in each model:
>>> b.i18n
{u'title_nl': u'Valk'}
# if a translation is not available, None is returned.
>>> print(b.title_de)
None
# fallback to the default language
>>> with override('de'):
...     b.title_i18n
'Falcon'
# now, if we set the German tranlation, it it is returned from title_i18n:
>>> b.title_de = 'Falk'
>>> with override('de'):
...     b.title_i18n
'Falk'

This is how to migrate from django-modeltranslation (version 0.12.1) to django-modeltrans:

1. Make sure you have a recent backup available!
2. Add modeltrans to your INSTALLED_APPS
3. Copy the django-modeltranslation registrations to use django-modeltrans alongside it, while disabling the virtual fields for now:

# if this whas your configuration:
from modeltranslation.translator import translator, TranslationOptions
from .models import Blog

class BlogTranslationOptions(TranslationOptions):
    fields = ('name', 'title', )

translator.register(Blog, BlogTranslationOptions)

# this is what you add:
def i18n_migrate():
    from modeltrans import translator, TranslationOptions

    translator.set_create_virtual_fields(False)


    class BlogTranslationOptions(TranslationOptions):
        fields = ('name', 'title', )

    translator.register(Blog, BlogTranslationOptions)


# and make sure it gets executed
i18n_migrate()

3. Run ./manage.py makemigrations <apps>. This will create the migration adding thei18n-fields required by django-modeltrans. Apply them with ./manage.py migrate

4. We need to create a migration to copy the values of the translated fields into the newly created i18n-field. django-modeltrans provides a management command to do that: ./manage.py i18n_makemmigrations <apps>

5. Now, remove django-modeltranslation by:

   • Removing the translation registrations for modeltranslation from your translation.py's. Also remove the function around the new registrations.
   • Remove the use of modeltranslation.admin.TranslationAdmin in your admin.py's

   Run ./manage.py makemigrations <apps>. This will remove the translated fields from your registered models. You can now safely remove the line translator.set_create_virtual_fields(False) and let django-modeltrans add the virtual fields to your models.

6. Update your code and cleanup:

   • Remove modeltranslation from INSTALLED_APPS.
   • Use <field>_i18n field names for places where you would use <field> with django-modeltranslation. Less magic, but explicit is better than implicit!

'''

tox

Running the tests only for the current environment, use make test

Some concepts and code from https://github.com/deschler/django-modeltranslation, which is in turn inspired by https://github.com/zmathew/django-linguo

We started this solution at Zostera because we did not like:

• The way django-modeltranslation adds one field per language (and thus requires a migration when adding language)
• The unpredictability of the original field.

Since JSONB is supported by Postgres now, we developed this approach.

• django-nence Also uses a jsonb PostgreSQL field, but has a bunch of custom QuerySet and Model methods to get translated values. It also requires one to inherit from a TranslationModel.
• django-i18nfield Stores JSON in a TextField, so does not allow lookup, searching or ordering by the translated fields.

• PostgreSQL jsonb functions