django-modeltranslation/modeltranslation/translator.py

198 lines
8 KiB
Python

# -*- coding: utf-8 -*-
from django.conf import settings
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,
TranslationFieldDescriptor,
create_translation_field)
from modeltranslation.utils import 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.localized_fieldnames = []
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:
# Create a dynamic translation field
translation_field = create_translation_field(model=model,\
field_name=field_name, lang=l[0])
# 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. 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,
translation_field)
localized_fields[field_name].append(localized_field_name)
return localized_fields
#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):
# model_class class -> translation_opts instance
self._registry = {}
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
model_fallback_values =\
getattr(translation_opts, 'fallback_values', None)
for field_name in translation_opts.fields:
if model_fallback_values is None:
field_fallback_value = None
elif isinstance(model_fallback_values, dict):
field_fallback_value =\
model_fallback_values.get(field_name, None)
else:
field_fallback_value = model_fallback_values
setattr(model, field_name, TranslationFieldDescriptor(field_name,\
fallback_value=field_fallback_value))
#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()