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The author of django-modeltranslation is Peter Eschler <peschler@gmail.com>
http://pyjax.net

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Copyright (c) 2009, Peter Eschler
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of the author nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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.. _ref-topics-modeltranslation:
===================
Model translation
===================
.. admonition:: About this document
This document provides an introduction to the modeltranslation application.
.. currentmodule:: modeltranslation.models
.. moduleauthor:: P. Eschler <peschler@googlemail.com>
The modeltranslation application can be used to translate existing models to
an arbitrary number of languages without having to change the original model
classes. It uses a registration approach (comparable to Django's
admin app) to be able to add translations to existing or new projects and is
fully integrated into the Django admin backend.
.. contents::
Features
========
- Unlimited number of target languages
- Add translations without changing existing models
- Django admin support
- ?Supports inherited models
Installation
============
To install the application please follow these steps. Each step is described
in detail in the following sections::
1. Add the ``modeltranslation`` app to the ``INSTALLED_APPS`` variable of your
project's ``settings.py``.
2. Configure your languages in the ``settings.py``.
3. Create a ``translation.py`` in your project directory and register
``TranslationOptions`` for every model you want to translate.
4. Sync the database using ``manage.py syncdb`` (note that this only applies
if the models registered in the ``translations.py`` did not have been
synced to the database before. If they did - read further down what to do
in that case.
Configure the project's ``settings.py``
---------------------------------------
The following variables have to be added to or edited in the project's
``settings.py``:
**settings.INSTALLED_APPS**
Make sure that the ``modeltranslation`` app is listed in your
``INSTALLED_APPS`` variable::
INSTALLED_APPS = (
...
'modeltranslation',
....
)
Also make sure that the app can be found on a path contained in your
``PYTHONPATH`` environment variable.
**settings.LANGUAGES**
The LANGUAGES variable must contain all languages used for translation. The
first language is treated as the *default language*.
The modeltranslation application uses the list of languages to add localized
fields to the models registered for translation. To use the languages ``de`` and
``en`` in your project, set the settings.LANGUAGES variable like this (where
``de`` is the default language)::
gettext = lambda s: s
LANGUAGES = (
('de', gettext('German')),
('en', gettext('English')),
)
Note that the ``gettext`` lambda function is not a feature of the
modeltranslation app, but rather required for Django to be able to
(statically) translate the verbose names of the languages using the standard
``i18n`` solution.
Registering models and their fields for translation
---------------------------------------------------
Registering models and their fields for translation requires the following
steps:
1. Create a ``translation.py`` in your project directory.
2. Create a translation option class for every model to translate.
3. Register the model and the translation option class at the
``modeltranslation.translator.translator``
The ``modeltranslation`` application reads the ``translation.py`` file in your
project directory thereby triggering the registration of the translation
options found in the file.
A translation option is a class that declares which fields of a model to
translate. The class must derive from ``modeltranslation.ModelTranslation``
and it must provide a ``fields`` attribute storing the list of fieldnames. The
option class must be registered with the
``modeltranslation.translator.translator`` instance.
.. note: In contrast to the Django admin application which looks for
``admin.py`` files in the project **and** application directories,
the modeltranslation app looks only for one ``translation.py`` file in
the project directory.
To illustrate this let's have a look at a simple example using a ``News`` model.
The news in this example only contains a ``title`` and a ``text`` field. Instead
of a news, this could be any Django model class::
class News(models.Model):
title = models.CharField(max_length=255)
text = models.TextField()
In order to tell the ``modeltranslation`` app to translate the ``title`` and
``text`` field, create a ``translation.py`` file in your project directory and
add the following::
from modeltranslation.translator import translator, TranslationOptions
from some.news.models import News
class NewsTranslationOptions(TranslationOptions):
fields = ('title', 'text',)
translator.register(News, NewsTranslationOptions)
Note that this does not require to change the ``News`` model in any way, it's
only imported. The ``NewsTranslationOptions`` derives from
``TranslationOptions`` and provides the ``fields`` attribute. Finally the model
and it's translation options are registered at the ``translator`` object.
Changes automatically applied to the model class
------------------------------------------------
At this point you are mostly done and the model classes registered for
translation will have been added some auto-magical fields. An SQL dump of the
News app example will look like this::
$ ./manage.py sqlall news
BEGIN;
CREATE TABLE `news_news` (
`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
`title` varchar(255) NOT NULL,
`title_de` varchar(255) NULL,
`title_en` varchar(255) NULL,
`text` longtext NULL,
`text_de` longtext NULL,
`text_en` longtext NULL,
)
;
ALTER TABLE `news_news` ADD CONSTRAINT page_id_refs_id_3edd1f0d FOREIGN KEY (`page_id`) REFERENCES `page_page` (`id`);
CREATE INDEX `news_news_page_id` ON `news_news` (`page_id`);
COMMIT;
Note the ``title_de``, ``title_en``, ``text_de`` and ``text_en`` fields which
are not declared in the original News model class but rather have been added by
the modeltranslation app. These are called *translation fields*. There will be
one for every language in your project's ``settings.py``.
The name of these additional fields is build using the original name of the
translated field and appending one of the language identifiers found in the
``settings.LANGUAGES``.
As these fields are added to the registered model class as fully valid Django
model fields, they will appear in the db schema for the model although it has
not been specified on the model explicitly. In case you are translating an
existing project and your models have already been synced to the database you
will need to alter the tables in your database and add these additional
translation fields.
.. _set_language: http://docs.djangoproject.com/en/dev/topics/i18n/#the-set-language-redirect-view
If you are starting a fresh project and have considered your translation needs
in the beginning then simply sync your database and you are ready to use
the translated models.
If you have added the translations to an existing project you have to edit your
database schema. Note that all added fields are declared ``null=True`` not
matter if the original field is required. In other words - all translations are
optional. To populate the default translation fields added by the
``modeltranslation`` application you can use the ``update_translation_fields``
command below. See the `The update_translation_fields command` section for more
infos on this.
The ``update_translation_fields`` command
-----------------------------------------
In case the modeltranslation app was installed on an existing project and you
have specified to translate fields of models which are already synced to the
database, you have to update your database schema manually.
Unfortunately the translation fields on the model will be empty then, and
your templates will show the translated value of the fields (see Rule 1 below)
which will be empty in this case. To correctly initialize the default
translation field you can use the ``update_translation_fields`` command::
manage.py update_translation_fields
Taken the News example from above this command will copy the value from the
news object's ``title`` field to the default translation field ``title_de``.
It only does so if the default translation field is empty otherwise nothing
is copied.
.. note: The command will examine your ``settings.LANGUAGES`` variable at the
first language declared there will be used as the default language.
By default all translated models (as specified in the project's
``translation.py`` will be populated with initial data. If you only want to
populate a specific model you can use the command with an additional app
name (the same as on e.g. the ``sqlall`` command)::
manage.py update_translation_fields news
Accessing translated and translation fields
===========================================
The ``modeltranslation`` app changes the behaviour of the translated fields. To
explain this consider the News example again. The original ``News`` model
looked like this::
class News(models.Model):
title = models.CharField(max_length=255)
text = models.TextField()
Now that it is registered with the ``modeltranslation`` app the model looks
like this - note the additional fields automatically added by the app::
class News(models.Model):
title = models.CharField(max_length=255) # original/translated field
title_de = models.CharField(null=True, blank=True, max_length=255) # default translation field
title_en = models.CharField(null=True, blank=True, max_length=255) # translation field
text = models.TextField() # original/translated field
text_de = models.TextField(null=True, blank=True) # default translation field
text_en = models.TextField(null=True, blank=True) # translation field
The example above assumes that the default language is ``de``, therefore the
``title_de`` and ``text_de`` fields are marked as the *default translation
fields*. If the default language is ``en``, the ``title_en`` and ``text_en``
fields would be the *default translation fields*.
Rules for translated field access
---------------------------------
So now when it comes to setting and getting the value of the original and the
translation fields the following rules apply:
**Rule 1**
Reading the value from the original field returns the value translated to the
*current language*.
**Rule 2**
Assigning a value to the original field also updates the value in the
associated default translation field.
**Rule 3**
Assigning a value to the default translation field also updates the original
field - note that the value of the original field will not be updated until the
model instance is saved.
**Rule 4**
If both fields - the original and the default translation field - are updated
at the same time, the default translation field wins.
Examples for translated field access
------------------------------------
Because the whole point of using the ``modeltranslation`` app is translating
dynamic content, the fields marked for translation are somehow special when it
comes to accessing them. The value returned by a translated field is depending
on the current language setting. "Language setting" is referring to the Django
`set_language`_ view and the corresponding ``get_lang`` function.
Assuming the current language is ``de`` in the News example from above, the
translated ``title`` field will return the value from the ``title_de`` field::
# Assuming the current language is "de"
n = News.objects.all()[0]
t = n.title # returns german translation
# Assuming the current language is "en"
t = n.title # returns english translation
This feature is implemented using Python descriptors making it happen without
the need to touch the original model classes in any way. The descriptor uses
the ``django.utils.i18n.get_language`` function to determine the current
language.
Django admin backend integration
================================
In order to be able to edit the translations via the admin backend you need to
register a special admin class for the translated models. The admin class must
derive from ``modeltranslation.admin.TranslationAdmin`` which does some funky
patching on all your models registered for translation::
from django.contrib import admin
from modeltranslation.admin import TranslationAdmin
class NewsAdmin(TranslationAdmin):
list_display = ('title',)
admin.site.register(News, NewsAdmin)
Tweaks applied to the admin
---------------------------
The ``TranslationAdmin`` class does only implement one special method which is
``def formfield_for_dbfield(self, db_field, **kwargs)``. This method does the
following:
1. Removes the original field from every admin form by setting it
``editable=False``.
2. Copies the widget of the original field to each of it's translation fields.
3. Checks if the - now removed - original field was required and if so makes the
default translation field required instead.
TranslationAdmin in combination with other admin classes
--------------------------------------------------------
If there already exists a custom admin class for a translated model and you
don't want or can't edit that class directly there is another solution.
Taken the News example let's say there is a ``NewsAdmin`` class defined by the
News app itself. This app is not yours or you don't want to touch it at all, but
it has this nice admin class::
class NewsAdmin(model.Admin):
def formfield_for_dbfield(self, db_field, **kwargs):
# does some funky stuff with the formfield here
So a first attempt might be to create your own admin class which subclasses
``NewsAdmin`` and ``TranslationAdmin`` to combine stuff like so::
class MyTranslatedNewsAdmin(NewsAdmin, TranslationAdmin):
pass
Unfortunately this won't work because Python can only execute one of the
``formfield_for_dbfield`` methods. Since both admin class implement this method
Python must make a decision and it chooses the first class ``NewsAdmin``. The
functionality from ``TranslationAdmin`` will not be executed and translation in
the admin will not work for this class.
But don't panic, here's a solution::
class MyTranslatedNewsAdmin(NewsAdmin, TranslationAdmin):
def formfield_for_dbfield(self, db_field, **kwargs):
field = super(MyTranslatedNewsAdmin, self).formfield_for_dbfield(db_field, **kwargs)
self.patch_translation_field(db_field, field, **kwargs)
return field
This implements the ``formfield_for_dbfield`` such that both functionalities
will be executed. The first line calls the superclass method which in this case
will be the one of ``NewsAdmin`` because it is the first class inherited from.
The ``TranslationAdmin`` capsulates all it's functionality in the
``patch_translation_field(db_field, field, **kwargs)`` method and the
``formfield_for_dbfield`` implementation of the ``TranslationAdmin`` class
simply calls it. You can copy this behaviour by calling it from a
custom admin class and that's done in the example above. After that the
``field`` is fully patched for translation and finally returned.
Caveats
=======
Consider the following example (assuming the default lanuage is ``de``)::
>>> n = News.objects.create(title="foo")
>>> n.title
'foo'
>>> n.title_de
>>>
Because the original field ``title`` was specified in the constructor it is
directly passed into the instance's ``__dict__`` and the descriptor which
normally updates the associated default translation field (``title_de``) is not
called. Therefor the call to ``n.title_de`` returns an empty value.
Now assign the title, which triggers the descriptor and the default translation
field is updated::
>>> n.title = 'foo'
>>> n.title_de
'foo'
>>>
Related projects
================
`django-multilingual`_
----------------------
A library providing support for multilingual content in Django models.
It is not possible to reuse existing models without modifying them.
`django-multilingual-model`_
----------------------------
A much simpler version of the above `django-multilingual`.
It works very similiar to the `django-multilingual` approach.
`transdb`_
----------
Django's field that stores labels in more than one language in database.
This approach uses a specialized ``Field`` class, which means one has to change
existing models.
`i18ndynamic`_
--------------
This approach is not developed any more.
`django-pluggable-model-i18n`_
------------------------------
This app utilizes a new approach to multilingual models based on the same
concept the new admin interface uses. A translation for an existing model can
be added by registering a translation class for that model.
This is more or less what ``modeltranslation`` does, unfortunately it is far
from being finished.
.. _django-multilingual: http://code.google.com/p/django-multilingual/
.. _django-multilingual-model: http://code.google.com/p/django-multilingual-model/
.. _django-transdb: http://code.google.com/p/transdb/
.. _i18ndynamic: http://code.google.com/p/i18ndynamic/
.. _django-pluggable-model-i18n: http://code.google.com/p/django-pluggable-model-i18n/

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from copy import deepcopy
from django.conf import settings
from django.contrib import admin
from django.contrib.contenttypes.models import ContentType
from django.forms import widgets
from django import forms, template
from django.forms.fields import MultiValueField
from django.shortcuts import get_object_or_404, render_to_response
from django.utils.safestring import mark_safe
from modeltranslation.translator import translator
class TranslationAdmin(admin.ModelAdmin):
def patch_translation_field(self, db_field, field, **kwargs):
trans_opts = translator.get_options_for_model(self.model)
# Hide the original field by making it non-editable.
if db_field.name in trans_opts.fields:
db_field.editable = False
# field.widget.attrs['readonly'] = "true"
# For every localized field copy the widget from the original field
if db_field.name in trans_opts.localized_fieldnames_rev:
orig_fieldname = trans_opts.localized_fieldnames_rev[db_field.name]
orig_formfield = self.formfield_for_dbfield(self.model._meta.get_field(orig_fieldname), **kwargs)
# In case the original form field was required, make the default
# translation field required instead.
if db_field.language == settings.LANGUAGES[0][0] and orig_formfield.required:
orig_formfield.required = False
field.required = True
field.widget = deepcopy(orig_formfield.widget)
def formfield_for_dbfield(self, db_field, **kwargs):
print "TranslationAdmin.formfield_for_dbfield"
# Call the baseclass function to get the formfield
field = super(TranslationAdmin, self).formfield_for_dbfield(db_field, **kwargs)
self.patch_translation_field(db_field, field, **kwargs)
#trans_opts = translator.get_options_for_model(self.model)
## Hide the original field by making it non-editable.
#if db_field.name in trans_opts.fields:
#db_field.editable = False
## field.widget.attrs['readonly'] = "true"
## For every localized field copy the widget from the original field
#if db_field.name in trans_opts.localized_fieldnames_rev:
#orig_fieldname = trans_opts.localized_fieldnames_rev[db_field.name]
#orig_formfield = self.formfield_for_dbfield(self.model._meta.get_field(orig_fieldname), **kwargs)
## In case the original form field was required, make the default
## translation field required instead.
#if db_field.language == settings.LANGUAGES[0][0] and orig_formfield.required:
#orig_formfield.required = False
#field.required = True
#field.widget = deepcopy(orig_formfield.widget)
return field
#def save_form(self, request, form, change):
#"""
#Given a ModelForm return an unsaved instance. ``change`` is True if
#the object is being changed, and False if it's being added.
#"""
#return form.save(commit=False)
#def save_model(self, request, obj, form, change):
#"""
#Given a model instance save it to the database.
#Because each translated field is wrapped with a descriptor to return
#the translated fields value (determined by the current language) we
#cannot set the field directly.
#To bypass the descriptor the assignment is done using the __dict__
#of the object.
#"""
#trans_opts = translator.get_options_for_model(self.model)
#for field_name in trans_opts.fields:
## Bypass the descriptor applied to the original field by setting
## it's value via the __dict__ (which doesn't call the descriptor).
#obj.__dict__[field_name] = form.cleaned_data[field_name]
## Call the baseclass method
#super(TranslationAdmin, self).save_model(request, obj, form, change)
#def render_change_form(self, request, context, add=False, change=False, form_url='', obj=None):
## Get the form from the context
#form = context['adminform'].form
## Get the translation options for the model of this admin view
#trans_opts = translator.get_options_for_model(self.model)
#if add:
#pass
#else:
#for fname in trans_opts.fields:
#field = form.fields[fname]
## print "here:", form.fields[fname]
#form.initial[fname] = obj.__dict__[fname]
#return super(TranslationAdmin, self).render_change_form(request, context, add, change, form_url, obj)

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from django.conf import settings
from django.db.models.fields import Field, CharField
from django.utils.translation import get_language
from modeltranslation.utils import build_localized_fieldname
class TranslationField(Field):
"""
The translation field functions as a proxy to the original field which is
wrapped.
For every field defined in the model's ``TranslationOptions`` localized
versions of that field are added to the model depending on the languages
given in ``settings.LANGUAGES``.
If for example there is a model ``News`` with a field ``title`` which is
registered for translation and the ``settings.LANGUAGES`` contains the
``de`` and ``en`` languages, the fields ``title_de`` and ``title_en`` will
be added to the model class. These fields are realized using this
descriptor.
The translation field needs to know which language it contains therefore
that needs to be specified when the field is created.
"""
def __init__(self, translated_field, language, *args, **kwargs):
# Store the originally wrapped field for later
self.translated_field = translated_field
self.language = language
# Update the dict of this field with the content of the original one
# This might be a bit radical?! Seems to work though...
self.__dict__.update(translated_field.__dict__)
# Translation are always optional (for now - maybe add some parameters
# to the translation options for configuring this)
self.null = True
self.blank = True
# Adjust the name of this field to reflect the language
self.attname = build_localized_fieldname(translated_field.name, language)
self.name = self.attname
# Copy the verbose name and append a language suffix (will e.g. in the
# admin). This might be a proxy function so we have to check that here.
if hasattr(translated_field.verbose_name, '_proxy____unicode_cast'):
verbose_name = translated_field.verbose_name._proxy____unicode_cast()
else:
verbose_name = translated_field.verbose_name
self.verbose_name = '%s [%s]' % (verbose_name, language)
def pre_save(self, model_instance, add):
val = super(TranslationField, self).pre_save(model_instance, add)
if get_language() == self.language and not add:
# Rule is: 3. Assigning a value to a translation field of the default language
# also updates the original field
model_instance.__dict__[self.translated_field.name] = val
#setattr(model_instance, self.attname, orig_val)
# Also return the original value
#return orig_val
return val
#def get_attname(self):
#return self.attname
def get_internal_type(self):
return self.translated_field.get_internal_type()
def contribute_to_class(self, cls, name):
super(TranslationField, self).contribute_to_class(cls, name)
#setattr(cls, 'get_%s_display' % self.name, curry(cls._get_FIELD_display, field=self))
#class CurrentLanguageField(CharField):
#def __init__(self, **kwargs):
#super(CurrentLanguageField, self).__init__(null=True, max_length=5, **kwargs)
#def contribute_to_class(self, cls, name):
#super(CurrentLanguageField, self).contribute_to_class(cls, name)
#registry = CurrentLanguageFieldRegistry()
#registry.add_field(cls, self)
#class CurrentLanguageFieldRegistry(object):
#_registry = {}
#def add_field(self, model, field):
#reg = self.__class__._registry.setdefault(model, [])
#reg.append(field)
#def get_fields(self, model):
#return self.__class__._registry.get(model, [])
#def __contains__(self, model):
#return model in self.__class__._registry

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# from django.db.models import signals
# from django.utils.functional import curry
#class TranslationMiddleware(object):
#def process_request(self, request):
#if hasattr(request, 'LANGUAGE_CODE'):
#print "TranslationMiddleware: preferred lang=", request.LANGUAGE_CODE
#update_lang = curry(self.update_lang, request.LANGUAGE_CODE)
#signals.pre_save.connect(update_lang, dispatch_uid=request, weak=False)
#else:
#print "TranslationMiddleware: no lang"
#pass
#def update_lang(self, lang, sender, instance, **kwargs):
#registry = registration.FieldRegistry()
#if sender in registry:
#for field in registry.get_fields(sender):
#setattr(instance, field.name, lang)
#def process_response(self, request, response):
#print "response:", dir(response)
#signals.pre_save.disconnect(dispatch_uid=request)
#return response

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from django.db import models
from modeltranslation.translator import translator
# Every model registered with the modeltranslation.translator.translator
# is patched to contain additional localized versions for every
# field specified in the model's translation options.
# Import the project's global "translation.py" which registers model
# classes and their translation options with the translator object.
# And because it must import the model classes for the registration
# process, the models.py modules of these apps are fully imported
try:
translation_mod = __import__('translation', {}, {}, [''])
except ImportError, exc:
print "No translation.py found in the project directory."
# After importing all translation modules, all translation classes are
# registered with the translator.
translated_app_names = ', '.join(t.__name__ for t in translator._registry.keys())
print "modeltranslation: registered %d applications for translation (%s)." % (len(translator._registry),
translated_app_names)

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from django.conf import settings
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.test import TestCase
from django.contrib.auth.models import User
from django.utils.translation import get_language
from django.utils.translation import trans_real
from django.utils.thread_support import currentThread
from modeltranslation import translator
class TestModel(models.Model):
title = models.CharField(max_length=255)
text = models.TextField(null=True)
class TestTranslationOptions(translator.TranslationOptions):
fields = ('title', 'text',)
translator.translator.register(TestModel, TestTranslationOptions)
class ModelTranslationTest(TestCase):
"Basic tests for the modeltranslation application."
urls = 'modeltranslation.testurls'
def setUp(self):
trans_real.activate("de")
def tearDown(self):
trans_real.deactivate()
def test_registration(self):
self.client.post('/set_language/', data={'language': 'de'})
#self.client.session['django_language'] = 'de-de'
#self.client.cookies[settings.LANGUAGE_COOKIE_NAME] = 'de-de'
langs = tuple(l[0] for l in settings.LANGUAGES)
self.failUnlessEqual(2, len(langs))
self.failUnless('de' in langs)
self.failUnless('en' in langs)
self.failUnless(translator.translator)
# Check that only one model is registered for translation
self.failUnlessEqual(len(translator.translator._registry), 1)
# Try to unregister a model that is not registered
self.assertRaises(translator.NotRegistered, translator.translator.unregister, User)
# Try to get options for a model that is not registered
self.assertRaises(translator.NotRegistered, translator.translator.get_options_for_model, User)
def test_translated_models(self):
# First create an instance of the test model to play with
inst = TestModel.objects.create(title="Testtitle", text="Testtext")
field_names = dir(inst)
self.failUnless('id' in field_names)
self.failUnless('title' in field_names)
self.failUnless('text' in field_names)
self.failUnless('title_de' in field_names)
self.failUnless('title_en' in field_names)
self.failUnless('text_de' in field_names)
self.failUnless('text_en' in field_names)
inst.delete()
def test_set_translation(self):
self.failUnlessEqual(get_language(), "de")
# First create an instance of the test model to play with
title1_de = "title de"
title1_en = "title en"
title2_de = "title2 de"
inst1 = TestModel(title_en=title1_en, text="Testtext")
inst1.title = title1_de
inst2 = TestModel(title=title2_de, text="Testtext")
inst1.save()
inst2.save()
self.failUnlessEqual(inst1.title, title1_de)
self.failUnlessEqual(inst1.title_en, title1_en)
self.failUnlessEqual(inst2.title, title2_de)
self.failUnlessEqual(inst2.title_en, None)
del inst1
del inst2
# Check that the translation fields are correctly saved and provide the
# correct value when retrieving them again.
n = TestModel.objects.get(title=title1_de)
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
def test_titleonly(self):
title1_de = "title de"
n = TestModel.objects.create(title=title1_de)
self.failUnlessEqual(n.title, title1_de)
# Because the original field "title" was specified in the constructor
# it is directly passed into the instance's __dict__ and the descriptor
# which updates the associated default translation field is not called
# and the default translation will be None.
self.failUnlessEqual(n.title_de, None)
self.failUnlessEqual(n.title_en, None)
# Now assign the title, that triggers the descriptor and the default
# translation field is updated
n.title = title1_de
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, None)
def test_rule1(self):
"""
Rule 1: Reading the value from the original field returns the value in
translated to the current language.
"""
title1_de = "title de"
title1_en = "title en"
text_de = "Dies ist ein deutscher Satz"
text_en = "This is an english sentence"
# Test 1.
n = TestModel.objects.create(title_de=title1_de, title_en=title1_en,
text_de=text_de, text_en=text_en)
n.save()
# language is set to "de" at this point
self.failUnlessEqual(get_language(), "de")
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
self.failUnlessEqual(n.text, text_de)
self.failUnlessEqual(n.text_de, text_de)
self.failUnlessEqual(n.text_en, text_en)
# Now switch to "en"
trans_real.activate("en")
self.failUnlessEqual(get_language(), "en")
# Title should now be return the english one (just by switching the
# language)
self.failUnlessEqual(n.title, title1_en)
self.failUnlessEqual(n.text, text_en)
n = TestModel.objects.create(title_de=title1_de, title_en=title1_en,
text_de=text_de, text_en=text_en)
n.save()
# language is set to "en" at this point
self.failUnlessEqual(n.title, title1_en)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
self.failUnlessEqual(n.text, text_en)
self.failUnlessEqual(n.text_de, text_de)
self.failUnlessEqual(n.text_en, text_en)
trans_real.activate("de")
self.failUnlessEqual(get_language(), "de")
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.text, text_de)
trans_real.deactivate()
def test_rule2(self):
"""
Rule 2: Assigning a value to the original field also updates the value
in the associated translation field of the default language
"""
self.failUnlessEqual(get_language(), "de")
title1_de = "title de"
title1_en = "title en"
n = TestModel.objects.create(title_de=title1_de, title_en=title1_en)
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
title2 = "Neuer Titel"
n.title = title2
n.save()
self.failUnlessEqual(n.title, title2)
self.failUnlessEqual(n.title, n.title_de)
trans_real.activate("en")
self.failUnlessEqual(get_language(), "en")
title3 = "new title"
n.title = title3
n.title_de = title1_de
n.save()
self.failUnlessEqual(n.title, title3)
self.failUnlessEqual(n.title, n.title_en)
self.failUnlessEqual(title1_de, n.title_de)
trans_real.deactivate()
def test_rule3(self):
"""
Rule 3: Assigning a value to a translation field of the default language
also updates the original field - note that the value of the original
field will not be updated until the model instance is saved.
"""
title1_de = "title de"
title1_en = "title en"
n = TestModel.objects.create(title_de=title1_de, title_en=title1_en)
self.failUnlessEqual(get_language(), "de")
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
n.title_de = "Neuer Titel"
n.save()
self.failUnlessEqual(n.title, n.title_de)
# Now switch to "en"
trans_real.activate("en")
self.failUnlessEqual(get_language(), "en")
n.title_en = "New title"
# the n.title field is not updated before the instance is saved
n.save()
self.failUnlessEqual(n.title, n.title_en)
trans_real.deactivate()
def test_rule4(self):
"""
Rule 4: If both fields - the original and the translation field of the
default language - are updated at the same time, the translation field
wins.
"""
self.failUnlessEqual(get_language(), "de")
title1_de = "title de"
title1_en = "title en"
n = TestModel.objects.create(title_de=title1_de, title_en=title1_en)
self.failUnlessEqual(n.title, title1_de)
self.failUnlessEqual(n.title_de, title1_de)
self.failUnlessEqual(n.title_en, title1_en)
title2_de = "neu de"
title2_en = "new en"
title_foo = "foo"
n.title = title_foo
n.title_de = title2_de
n.title_en = title2_en
n.save()
self.failUnlessEqual(n.title, title2_de)
self.failUnlessEqual(n.title_de, title2_de)
self.failUnlessEqual(n.title_en, title2_en)
n.title = title_foo
n.save()
self.failUnlessEqual(n.title, title_foo)
self.failUnlessEqual(n.title_de, title_foo)
self.failUnlessEqual(n.title_en, title2_en)

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from django.conf.urls.defaults import *
from django.contrib import admin
from django.views.generic.simple import direct_to_template
urlpatterns = patterns('',
url(r'^set_language/$',
'django.views.i18n.set_language',
{},
name='set_language'),
)

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from django.conf import settings
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.db.models import signals
from django.db.models.base import ModelBase
from django.utils.functional import curry
from modeltranslation.fields import TranslationField
from modeltranslation.utils import TranslationFieldDescriptor, build_localized_fieldname
class AlreadyRegistered(Exception):
pass
class NotRegistered(Exception):
pass
class TranslationOptions(object):
"""
The TranslationOptions object is used to specify the fields to translate.
The options are registered in combination with a model class at the
``modeltranslation.translator.translator`` instance.
It caches the content type of the translated model for faster lookup later
on.
"""
def __init__(self, *args, **kwargs):
# self.translation_model = None
self.model_ct = None
self.localized_fieldnames = list()
#def get_localized_fieldnames(model):
def add_localized_fields(model):
"""
Monkey patchs the original model class to provide additional fields for
every language. Only do that for fields which are defined in the
translation options of the model.
Returns a dict mapping the original fieldname to a list containing the names
of the localized fields created for the original field.
"""
localized_fields = dict()
translation_opts = translator.get_options_for_model(model)
for field_name in translation_opts.fields:
localized_fields[field_name] = list()
for l in settings.LANGUAGES:
# Construct the name for the localized field
localized_field_name = build_localized_fieldname(field_name, l[0])
# Check if the model already has a field by that name
if hasattr(model, localized_field_name):
raise ValueError("Error adding translation field. The model "\
"'%s' already contains a field named '%s'. "\
% (instance.__class__.__name__, localized_field_name))
# This approach implements the translation fields as full valid
# django model fields and therefore adds them via add_to_class
localized_field = model.add_to_class(localized_field_name,
TranslationField(model._meta.get_field(field_name),
l[0]))
localized_fields[field_name].append(localized_field_name)
return localized_fields
# model.add_to_class('current_language', CurrentLanguageField())
#def translated_model_initialized(field_names, instance, **kwargs):
#print "translated_model_initialized instance:", instance, ", field:", field_names
#for field_name in field_names:
#initial_val = getattr(instance, field_name)
#print " field: %s, initialval: %s" % (field_name, initial_val)
#setattr(instance.__class__, field_name, TranslationFieldDescriptor(field_name,
#initial_val))
#def translated_model_initializing(sender, args, kwargs, **signal_kwargs):
#print "translated_model_initializing", sender, args, kwargs
#trans_opts = translator.get_options_for_model(sender)
#for field_name in trans_opts.fields:
#setattr(sender, field_name, TranslationFieldDescriptor(field_name))
class Translator(object):
"""
A Translator object encapsulates an instance of a translator. Models are
registered with the Translator using the register() method.
"""
def __init__(self):
self._registry = {} # model_class class -> translation_opts instance
def register(self, model_or_iterable, translation_opts, **options):
"""
Registers the given model(s) with the given translation options.
The model(s) should be Model classes, not instances.
If a model is already registered for translation, this will raise
AlreadyRegistered.
"""
# Don't import the humongous validation code unless required
if translation_opts and settings.DEBUG:
from django.contrib.admin.validation import validate
else:
validate = lambda model, adminclass: None
#if not translation_opts:
#translation_opts = TranslationOptions
if isinstance(model_or_iterable, ModelBase):
model_or_iterable = [model_or_iterable]
for model in model_or_iterable:
if model in self._registry:
raise AlreadyRegistered('The model %s is already registered for translation' % model.__name__)
# If we got **options then dynamically construct a subclass of
# translation_opts with those **options.
if options:
# For reasons I don't quite understand, without a __module__
# the created class appears to "live" in the wrong place,
# which causes issues later on.
options['__module__'] = __name__
translation_opts = type("%sAdmin" % model.__name__, (translation_opts,), options)
# Validate (which might be a no-op)
#validate(translation_opts, model)
# Store the translation class associated to the model
self._registry[model] = translation_opts
# Get the content type of the original model and store it on the
# translation options for faster lookup later on.
translation_opts.model_ct = ContentType.objects.get_for_model(model)
# Add the localized fields to the model and store the names of these
# fields in the model's translation options for faster lookup later
# on.
translation_opts.localized_fieldnames = add_localized_fields(model)
# Create a reverse dict mapping the localized_fieldnames to the
# original fieldname
rev_dict = dict()
for orig_name, loc_names in translation_opts.localized_fieldnames.items():
for ln in loc_names:
rev_dict[ln] = orig_name
translation_opts.localized_fieldnames_rev = rev_dict
print "Applying descriptor field for model %s" % model
for field_name in translation_opts.fields:
setattr(model, field_name, TranslationFieldDescriptor(field_name))
#signals.pre_init.connect(translated_model_initializing, sender=model, weak=False)
def unregister(self, model_or_iterable):
"""
Unregisters the given model(s).
If a model isn't already registered, this will raise NotRegistered.
"""
if isinstance(model_or_iterable, ModelBase):
model_or_iterable = [model_or_iterable]
for model in model_or_iterable:
if model not in self._registry:
raise NotRegistered('The model "%s" is not registered for translation' % model.__name__)
del self._registry[model]
def get_options_for_model(self, model):
"""
Returns the translation options for the given ``model``. If the
``model`` is not registered a ``NotRegistered`` exception is raised.
"""
try:
return self._registry[model]
except KeyError:
raise NotRegistered('The model "%s" is not registered for translation' % model.__name__)
# This global object represents the singleton translator object
translator = Translator()

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from django.db import models
from django.conf import settings
from django.core.exceptions import ValidationError
from django.contrib.contenttypes.models import ContentType
from django.utils.translation import get_language
class TranslationFieldDescriptor(object):
"""
A descriptor used for the original translated field.
"""
def __init__(self, name, initial_val=""):
"""
The ``name`` is the name of the field (which is not available in the
descriptor by default - this is Python behaviour).
"""
self.name = name
self.val = initial_val
def __set__(self, instance, value):
# print "Descriptor.__set__%s %s %s.%s: %s" % (id(instance), id(self), type(instance), self.name, value)
lang = get_language()
loc_field_name = build_localized_fieldname(self.name, lang)
# also update the translation field of the current language
setattr(instance, loc_field_name, value)
# update the original field via the __dict__ to prevent calling the
# descriptor
instance.__dict__[self.name] = value
def __get__(self, instance, owner):
# print "Descriptor.__get__%s %s %s.%s: %s" % (id(instance), id(self), type(instance), self.name, self.val)
if not instance:
raise ValueError(u"Translation field '%s' can only be "\
"accessed via an instance not via "\
"a class." % self.name)
lang = get_language()
loc_field_name = build_localized_fieldname(self.name, lang)
if hasattr(instance, loc_field_name):
return getattr(instance, loc_field_name) or instance.__dict__[self.name]
return instance.__dict__[self.name]
#def create_model(name, fields=None, app_label='', module='', options=None, admin_opts=None):
#"""
#Create specified model.
#This is taken from http://code.djangoproject.com/wiki/DynamicModels
#"""
#class Meta:
## Using type('Meta', ...) gives a dictproxy error during model creation
#pass
#if app_label:
## app_label must be set using the Meta inner class
#setattr(Meta, 'app_label', app_label)
## Update Meta with any options that were provided
#if options is not None:
#for key, value in options.iteritems():
#setattr(Meta, key, value)
## Set up a dictionary to simulate declarations within a class
#attrs = {'__module__': module, 'Meta': Meta}
## Add in any fields that were provided
#if fields:
#attrs.update(fields)
## Create the class, which automatically triggers ModelBase processing
#model = type(name, (models.Model,), attrs)
## Create an Admin class if admin options were provided
#if admin_opts is not None:
#class Admin(admin.ModelAdmin):
#pass
#for key, value in admin_opts:
#setattr(Admin, key, value)
#admin.site.register(model, Admin)
#return model
def copy_field(field):
"""Instantiate a new field, with all of the values from the old one, except the
to and to_field in the case of related fields.
This taken from http://www.djangosnippets.org/snippets/442/
"""
base_kw = dict([(n, getattr(field,n, '_null')) for n in models.fields.Field.__init__.im_func.func_code.co_varnames])
if isinstance(field, models.fields.related.RelatedField):
rel = base_kw.get('rel')
rel_kw = dict([(n, getattr(rel,n, '_null')) for n in rel.__init__.im_func.func_code.co_varnames])
if isinstance(field, models.fields.related.ForeignKey):
base_kw['to_field'] = rel_kw.pop('field_name')
base_kw.update(rel_kw)
base_kw.pop('self')
return field.__class__(**base_kw)
def build_localized_fieldname(field_name, lang):
return '%s_%s' % (field_name, lang)

0
modeltranslation/views.py Normal file
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