# -*- coding: utf-8 -*- from django.conf import settings from django.db.models import Manager from django.db.models.base import ModelBase from modeltranslation.fields import (TranslationFieldDescriptor, create_translation_field) from modeltranslation.manager import MultilingualManager, rewrite_lookup_key from modeltranslation.utils import build_localized_fieldname, unique class AlreadyRegistered(Exception): pass class NotRegistered(Exception): pass class FieldsAggregationMetaClass(type): """ Meta class to handle inheritance of fields between classes """ def __new__(cls, name, bases, attrs): parents = [b for b in bases if isinstance(b, FieldsAggregationMetaClass)] if not parents: return super(FieldsAggregationMetaClass, cls).__new__(cls, name, bases, attrs) attrs['fields'] = tuple(attrs.get('fields', ())) for base in parents: attrs['fields'] += tuple(base.fields) attrs['fields'] = tuple(unique(attrs['fields'])) return super(FieldsAggregationMetaClass, cls).__new__(cls, name, bases, attrs) 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. """ __metaclass__ = FieldsAggregationMetaClass fields = () def __init__(self, *args, **kwargs): self.localized_fieldnames = [] def add_localized_fields(model): """ Monkey patches 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'." % ( model._meta.object_name, localized_field_name)) # This approach implements the translation fields as full valid # django model fields and therefore adds them via add_to_class model.add_to_class(localized_field_name, translation_field) localized_fields[field_name].append(localized_field_name) return localized_fields def add_manager(model): """ Monkey patches the original model to use MultilingualManager instead of default manager (``objects``). If model has a custom manager, then merge it with MultilingualManager. """ if not hasattr(model, 'objects'): return current_manager = model.objects if isinstance(current_manager, MultilingualManager): return if current_manager.__class__ is Manager: current_manager.__class__ = MultilingualManager else: class NewMultilingualManager(current_manager.__class__, MultilingualManager): pass current_manager.__class__ = NewMultilingualManager def patch_constructor(model): """ Monkey patches the original model to rewrite fields names in __init__ """ old_init = model.__init__ def new_init(self, *args, **kwargs): for key, val in kwargs.items(): new_key = rewrite_lookup_key(model, key) # Old key is intentionally left in case old_init wants to play with it kwargs.setdefault(new_key, val) old_init(self, *args, **kwargs) model.__init__ = new_init #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)) def delete_cache_fields(model): opts = model._meta try: del opts._field_cache except AttributeError: pass try: del opts._field_name_cache except AttributeError: pass try: del opts._name_map except AttributeError: pass 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. """ 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( "%sTranslationOptions" % model.__name__, (translation_opts,), options) # Store the translation class associated to the model self._registry[model] = translation_opts # 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 # Delete all fields cache for related model (parent and children) for related_obj in model._meta.get_all_related_objects(): delete_cache_fields(related_obj.model) # Set MultilingualManager add_manager(model) # Patch __init__ to rewrite fields patch_constructor(model) # Substitute original field with descriptor model_fallback_values = getattr( translation_opts, 'fallback_values', None) model_fallback_languages = getattr( translation_opts, 'fallback_languages', 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 descriptor = TranslationFieldDescriptor( model._meta.get_field(field_name), fallback_value=field_fallback_value, fallback_languages=model_fallback_languages) setattr(model, field_name, descriptor) #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: # Try to find a localized parent model and build a dedicated # translation options class with the parent info. # Useful when a ModelB inherits from ModelA and only ModelA fields # are localized. No need to register ModelB. fields = set() localized_fieldnames = {} localized_fieldnames_rev = {} for parent in model._meta.parents.keys(): if parent in self._registry: trans_opts = self._registry[parent] fields.update(trans_opts.fields) localized_fieldnames.update( trans_opts.localized_fieldnames) localized_fieldnames_rev.update( trans_opts.localized_fieldnames_rev) if fields and localized_fieldnames and localized_fieldnames_rev: options = { '__module__': __name__, 'fields': tuple(fields), 'localized_fieldnames': localized_fieldnames, 'localized_fieldnames_rev': localized_fieldnames_rev } translation_opts = type( "%sTranslation" % model.__name__, (TranslationOptions,), options) # delete_cache_fields(model) return translation_opts raise NotRegistered('The model "%s" is not registered for ' 'translation' % model.__name__) # This global object represents the singleton translator object translator = Translator()