# -*- 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 class AlreadyRegistered(Exception): pass class NotRegistered(Exception): pass class DescendantRegistered(Exception): pass class FieldsAggregationMetaClass(type): """ Metaclass to handle custom inheritance of fields between classes. """ def __new__(cls, name, bases, attrs): attrs['fields'] = set(attrs.get('fields', ())) for base in bases: if isinstance(base, FieldsAggregationMetaClass): attrs['fields'].update(base.fields) attrs['fields'] = tuple(attrs['fields']) return super(FieldsAggregationMetaClass, cls).__new__(cls, name, bases, attrs) class TranslationOptions(object): """ Translatable fields are declared by registering a model using ``TranslationOptions`` class with appropriate ``fields`` attribute. Model-specific fallback values and languages can also be given as class attributes. Options instances hold info about translatable fields for a model and its superclasses. The ``local_fields`` and ``fields`` attributes are mappings from fields to sets of their translation fields; ``local_fields`` contains only those fields that are handled in the model's database table (those inherited from abstract superclasses, unless there is a concrete superclass in between in the inheritance chain), while ``fields`` also includes fields inherited from concrete supermodels (giving all translated fields available on a model). """ __metaclass__ = FieldsAggregationMetaClass def __init__(self, model): """ Create fields dicts without any translation fields. """ self.model = model self.registered = False self.local_fields = dict((f, set()) for f in self.fields) self.fields = dict((f, set()) for f in self.fields) def update(self, other): """ Update with options from a superclass. """ if other.model._meta.abstract: self.local_fields.update(other.local_fields) self.fields.update(other.fields) def add_translation_field(self, field, translation_field): """ Add a new translation field to both fields dicts. """ self.local_fields[field].add(translation_field) self.fields[field].add(translation_field) def __str__(self): local = tuple(self.local_fields.keys()) inherited = tuple(set(self.fields.keys()) - set(local)) return '%s: %s + %s' % (self.__class__.__name__, local, inherited) def add_translation_fields(model, opts): """ Monkey patches the original model class to provide additional fields for every language. Adds newly created translation fields to the given translation options. """ for field_name in opts.local_fields.iterkeys(): 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) opts.add_translation_field(field_name, translation_field) 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(MultilingualManager, current_manager.__class__): 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.local_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): # All seen models (model class -> ``TranslationOptions`` instance). self._registry = {} def register(self, model_or_iterable, opts_class=None, **options): """ Registers the given model(s) with the given translation options. The model(s) should be Model classes, not instances. Fields declared for translation on a base class are inherited by subclasses. If the model or one of its subclasses is already registered for translation, this will raise an exception. """ if isinstance(model_or_iterable, ModelBase): model_or_iterable = [model_or_iterable] for model in model_or_iterable: # Ensure that a base is not registered after a subclass (_registry # is closed with respect to taking bases, so we can just check if # we've seen the model). if model in self._registry: if self._registry[model].registered: raise AlreadyRegistered( 'Model "%s" is already registered for translation' % model.__name__) else: descendants = [d.__name__ for d in self._registry.keys() if issubclass(d, model) and d != model] raise DescendantRegistered( 'Model "%s" cannot be registered after its subclass' ' "%s"' % (model.__name__, descendants[0])) # Find inherited fields and create options instance for the model. opts = self._get_options_for_model(model, opts_class, **options) # Mark the object explicitly as registered -- registry caches # options of all models, registered or not. opts.registered = True # Add translation fields to the model. add_translation_fields(model, opts) # 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(opts, 'fallback_values', None) model_fallback_languages = getattr(opts, 'fallback_languages', None) for field_name in opts.local_fields.iterkeys(): 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 registered, this will raise NotRegistered. If one of its subclasses is registered, DescendantRegistered will be raised. """ if isinstance(model_or_iterable, ModelBase): model_or_iterable = [model_or_iterable] for model in model_or_iterable: # Check if the model is actually registered (``get_options_for_model`` # throws an exception if it's not). self.get_options_for_model(model) # Invalidate all submodels options and forget about # the model itself. for desc, desc_opts in self._registry.items(): if not issubclass(desc, model): continue if model != desc and desc_opts.registered: # Allowing to unregister a base would necessitate # repatching all submodels. raise DescendantRegistered( 'You need to unregister descendant "%s" before' ' unregistering its base "%s"' % (desc.__name__, model.__name__)) del self._registry[desc] def get_registered_models(self, abstract=True): """ Returns a list of all registered models, or just concrete registered models. """ return [model for (model, opts) in self._registry.items() if opts.registered and (not model._meta.abstract or abstract)] def _get_options_for_model(self, model, opts_class=None, **options): """ Returns an instance of translation options with translated fields defined for the ``model`` and inherited from superclasses. """ if model not in self._registry: # Create a new type for backwards compatibility. opts = type("%sTranslationOptions" % model.__name__, (opts_class or TranslationOptions,), options)(model) # Fields for translation may be inherited from abstract # superclasses, so we need to look at all parents. for base in model.__bases__: if not hasattr(base, '_meta'): # Things without _meta aren't functional models, so they're # uninteresting parents. continue opts.update(self._get_options_for_model(base)) # Cache options for all models -- we may want to compute options # of registered subclasses of unregistered models. self._registry[model] = opts return self._registry[model] def get_options_for_model(self, model): """ Thin wrapper around ``_get_options_for_model`` to preserve the semantic of throwing exception for models not directly registered. """ opts = self._get_options_for_model(model) if not opts.registered: raise NotRegistered('The model "%s" is not registered for ' 'translation' % model.__name__) return opts # This global object represents the singleton translator object translator = Translator()