mirror of
https://github.com/Hopiu/django-modeltranslation.git
synced 2026-04-24 15:04:44 +00:00
477 lines
20 KiB
Python
477 lines
20 KiB
Python
# -*- coding: utf-8 -*-
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from django.utils.six import with_metaclass
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from django.db.models import Manager, ForeignKey, OneToOneField
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from django.db.models.base import ModelBase
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from django.db.models.signals import post_init
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from modeltranslation import settings as mt_settings
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from modeltranslation.fields import (NONE, create_translation_field, TranslationFieldDescriptor,
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TranslatedRelationIdDescriptor,
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LanguageCacheSingleObjectDescriptor)
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from modeltranslation.manager import MultilingualManager, rewrite_lookup_key
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from modeltranslation.utils import build_localized_fieldname, parse_field
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class AlreadyRegistered(Exception):
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pass
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class NotRegistered(Exception):
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pass
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class DescendantRegistered(Exception):
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pass
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class FieldsAggregationMetaClass(type):
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"""
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Metaclass to handle custom inheritance of fields between classes.
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"""
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def __new__(cls, name, bases, attrs):
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attrs['fields'] = set(attrs.get('fields', ()))
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for base in bases:
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if isinstance(base, FieldsAggregationMetaClass):
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attrs['fields'].update(base.fields)
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attrs['fields'] = tuple(attrs['fields'])
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return super(FieldsAggregationMetaClass, cls).__new__(cls, name, bases, attrs)
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class TranslationOptions(with_metaclass(FieldsAggregationMetaClass, object)):
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"""
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Translatable fields are declared by registering a model using
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``TranslationOptions`` class with appropriate ``fields`` attribute.
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Model-specific fallback values and languages can also be given as class
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attributes.
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Options instances hold info about translatable fields for a model and its
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superclasses. The ``local_fields`` and ``fields`` attributes are mappings
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from fields to sets of their translation fields; ``local_fields`` contains
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only those fields that are handled in the model's database table (those
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inherited from abstract superclasses, unless there is a concrete superclass
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in between in the inheritance chain), while ``fields`` also includes fields
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inherited from concrete supermodels (giving all translated fields available
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on a model).
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``related`` attribute inform whether this model is related part of some relation
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with translated model. This model may be not translated itself.
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``related_fields`` contains names of reverse lookup fields.
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"""
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def __init__(self, model):
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"""
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Create fields dicts without any translation fields.
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"""
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self.model = model
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self.registered = False
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self.related = False
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self.local_fields = dict((f, set()) for f in self.fields)
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self.fields = dict((f, set()) for f in self.fields)
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self.related_fields = []
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def update(self, other):
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"""
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Update with options from a superclass.
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"""
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if other.model._meta.abstract:
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self.local_fields.update(other.local_fields)
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self.fields.update(other.fields)
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def add_translation_field(self, field, translation_field):
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"""
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Add a new translation field to both fields dicts.
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"""
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self.local_fields[field].add(translation_field)
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self.fields[field].add(translation_field)
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def get_field_names(self):
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"""
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Return name of all fields that can be used in filtering.
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"""
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return list(self.fields.keys()) + self.related_fields
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def __str__(self):
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local = tuple(self.local_fields.keys())
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inherited = tuple(set(self.fields.keys()) - set(local))
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return '%s: %s + %s' % (self.__class__.__name__, local, inherited)
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def add_translation_fields(model, opts):
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"""
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Monkey patches the original model class to provide additional fields for
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every language.
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Adds newly created translation fields to the given translation options.
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"""
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model_empty_values = getattr(opts, 'empty_values', NONE)
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for field_name in opts.local_fields.keys():
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field_empty_value = parse_field(model_empty_values, field_name, NONE)
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for l in mt_settings.AVAILABLE_LANGUAGES:
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# Create a dynamic translation field
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translation_field = create_translation_field(
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model=model, field_name=field_name, lang=l, empty_value=field_empty_value)
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# Construct the name for the localized field
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localized_field_name = build_localized_fieldname(field_name, l)
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# Check if the model already has a field by that name
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if hasattr(model, localized_field_name):
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raise ValueError(
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"Error adding translation field. Model '%s' already contains a field named"
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"'%s'." % (model._meta.object_name, localized_field_name))
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# This approach implements the translation fields as full valid
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# django model fields and therefore adds them via add_to_class
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model.add_to_class(localized_field_name, translation_field)
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opts.add_translation_field(field_name, translation_field)
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# Rebuild information about parents fields. If there are opts.local_fields, field cache would be
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# invalidated (by model._meta.add_field() function). Otherwise, we need to do it manually.
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if len(opts.local_fields) == 0:
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model._meta._fill_fields_cache()
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def add_manager(model):
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"""
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Monkey patches the original model to use MultilingualManager instead of
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default managers (not only ``objects``, but also every manager defined and inherited).
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Custom managers are merged with MultilingualManager.
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"""
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if model._meta.abstract:
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return
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for _, attname, cls in model._meta.concrete_managers + model._meta.abstract_managers:
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current_manager = getattr(model, attname)
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if isinstance(current_manager, MultilingualManager):
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continue
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prev_class = current_manager.__class__
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if current_manager.__class__ is Manager:
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current_manager.__class__ = MultilingualManager
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else:
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class NewMultilingualManager(MultilingualManager, current_manager.__class__):
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pass
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current_manager.__class__ = NewMultilingualManager
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if model._default_manager.__class__ is prev_class:
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# Normally model._default_manager is a reference to one of model's managers
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# (and would be patched by the way).
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# However, in some rare situations (mostly proxy models)
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# model._default_manager is not the same instance as one of managers, but it
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# share the same class.
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model._default_manager.__class__ = current_manager.__class__
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def patch_constructor(model):
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"""
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Monkey patches the original model to rewrite fields names in __init__
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"""
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old_init = model.__init__
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def new_init(self, *args, **kwargs):
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self._mt_init = True
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if not self._deferred:
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populate_translation_fields(self.__class__, kwargs)
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for key, val in list(kwargs.items()):
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new_key = rewrite_lookup_key(model, key)
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# Old key is intentionally left in case old_init wants to play with it
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kwargs.setdefault(new_key, val)
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old_init(self, *args, **kwargs)
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model.__init__ = new_init
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def delete_mt_init(sender, instance, **kwargs):
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if hasattr(instance, '_mt_init'):
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del instance._mt_init
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def patch_clean_fields(model):
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"""
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Patch clean_fields method to handle different form types submission.
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"""
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old_clean_fields = model.clean_fields
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def new_clean_fields(self, exclude=None):
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if hasattr(self, '_mt_form_pending_clear'):
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# Some form translation fields has been marked as clearing value.
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# Check if corresponding translated field was also saved (not excluded):
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# - if yes, it seems like form for MT-unaware app. Ignore clearing (left value from
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# translated field unchanged), as if field was omitted from form
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# - if no, then proceed as normally: clear the field
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for field_name, value in self._mt_form_pending_clear.items():
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field = self._meta.get_field(field_name)
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orig_field_name = field.translated_field.name
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if orig_field_name in exclude:
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field.save_form_data(self, value, check=False)
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delattr(self, '_mt_form_pending_clear')
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old_clean_fields(self, exclude)
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model.clean_fields = new_clean_fields
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def patch_metaclass(model):
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"""
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Monkey patches original model metaclass to exclude translated fields on deferred subclasses.
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"""
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old_mcs = model.__class__
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class translation_deferred_mcs(old_mcs):
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"""
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This metaclass is essential for deferred subclasses (obtained via only/defer) to work.
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When deferred subclass is created, some translated fields descriptors could be overridden
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by DeferredAttribute - which would cause translation retrieval to fail.
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Prevent this from happening with deleting those attributes from class being created.
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This metaclass would be called from django.db.models.query_utils.deferred_class_factory
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"""
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def __new__(cls, name, bases, attrs):
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if attrs.get('_deferred', False):
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opts = translator.get_options_for_model(model)
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for field_name in opts.fields.keys():
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attrs.pop(field_name, None)
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return super(translation_deferred_mcs, cls).__new__(cls, name, bases, attrs)
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# Assign to __metaclass__ wouldn't work, since metaclass search algorithm check for __class__.
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# http://docs.python.org/2/reference/datamodel.html#__metaclass__
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model.__class__ = translation_deferred_mcs
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def delete_cache_fields(model):
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opts = model._meta
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cached_attrs = ('_field_cache', '_field_name_cache', '_name_map', 'fields', 'concrete_fields',
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'local_concrete_fields')
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for attr in cached_attrs:
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try:
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delattr(opts, attr)
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except AttributeError:
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pass
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def populate_translation_fields(sender, kwargs):
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"""
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When models are created or loaded from fixtures, replicates values
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provided for translatable fields to some / all empty translation fields,
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according to the current population mode.
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Population is performed only on keys (field names) present in kwargs.
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Nothing is returned, but passed kwargs dictionary is altered.
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With ``mode`` set to:
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-- ``all``: fills all translation fields, skipping just those for
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which a translated value is also provided;
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-- ``default``: fills only the default translation (unless it is
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additionally provided);
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-- ``required``: like ``default``, but only if the original field is
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non-nullable;
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At least the ``required`` mode should be used when loading untranslated
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fixtures to keep the database consistent (note that Django management
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commands are normally forced to run with hardcoded ``en-us`` language
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active). The ``default`` mode is useful if you need to ensure fallback
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values are available, and ``all`` if you need to have all translations
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defined (for example to make lookups / filtering without resorting to
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query fallbacks).
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"""
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populate = mt_settings.AUTO_POPULATE
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if not populate:
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return
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if populate is True:
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# What was meant by ``True`` is now called ``all``.
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populate = 'all'
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opts = translator.get_options_for_model(sender)
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for key, val in list(kwargs.items()):
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if key in opts.fields:
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if populate == 'all':
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# Set the value for every language.
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for translation_field in opts.fields[key]:
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kwargs.setdefault(translation_field.name, val)
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elif populate == 'default':
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default = build_localized_fieldname(key, mt_settings.DEFAULT_LANGUAGE)
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kwargs.setdefault(default, val)
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elif populate == 'required':
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default = build_localized_fieldname(key, mt_settings.DEFAULT_LANGUAGE)
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if not sender._meta.get_field(key).null:
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kwargs.setdefault(default, val)
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else:
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raise AttributeError("Unknown population mode '%s'." % populate)
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def patch_related_object_descriptor_caching(ro_descriptor):
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"""
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Patch SingleRelatedObjectDescriptor or ReverseSingleRelatedObjectDescriptor to use
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language-aware caching.
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"""
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class NewSingleObjectDescriptor(LanguageCacheSingleObjectDescriptor, ro_descriptor.__class__):
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pass
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ro_descriptor.accessor = ro_descriptor.related.get_accessor_name()
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ro_descriptor.__class__ = NewSingleObjectDescriptor
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class Translator(object):
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"""
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A Translator object encapsulates an instance of a translator. Models are
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registered with the Translator using the register() method.
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"""
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def __init__(self):
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# All seen models (model class -> ``TranslationOptions`` instance).
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self._registry = {}
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def register(self, model_or_iterable, opts_class=None, **options):
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"""
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Registers the given model(s) with the given translation options.
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The model(s) should be Model classes, not instances.
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Fields declared for translation on a base class are inherited by
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subclasses. If the model or one of its subclasses is already
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registered for translation, this will raise an exception.
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"""
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if isinstance(model_or_iterable, ModelBase):
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model_or_iterable = [model_or_iterable]
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for model in model_or_iterable:
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# Ensure that a base is not registered after a subclass (_registry
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# is closed with respect to taking bases, so we can just check if
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# we've seen the model).
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if model in self._registry:
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if self._registry[model].registered:
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raise AlreadyRegistered(
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'Model "%s" is already registered for translation' %
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model.__name__)
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else:
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descendants = [d.__name__ for d in self._registry.keys()
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if issubclass(d, model) and d != model]
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raise DescendantRegistered(
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'Model "%s" cannot be registered after its subclass'
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' "%s"' % (model.__name__, descendants[0]))
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# Find inherited fields and create options instance for the model.
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opts = self._get_options_for_model(model, opts_class, **options)
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# Mark the object explicitly as registered -- registry caches
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# options of all models, registered or not.
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opts.registered = True
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# Add translation fields to the model.
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add_translation_fields(model, opts)
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# Delete all fields cache for related model (parent and children)
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for related_obj in model._meta.get_all_related_objects():
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delete_cache_fields(related_obj.model)
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# Set MultilingualManager
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add_manager(model)
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# Patch __init__ to rewrite fields
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patch_constructor(model)
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# Connect signal for model
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post_init.connect(delete_mt_init, sender=model)
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# Patch clean_fields to verify form field clearing
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patch_clean_fields(model)
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# Patch __metaclass__ to allow deferring to work
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patch_metaclass(model)
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# Substitute original field with descriptor
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model_fallback_languages = getattr(opts, 'fallback_languages', None)
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model_fallback_values = getattr(opts, 'fallback_values', NONE)
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model_fallback_undefined = getattr(opts, 'fallback_undefined', NONE)
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for field_name in opts.local_fields.keys():
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field = model._meta.get_field(field_name)
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field_fallback_value = parse_field(model_fallback_values, field_name, NONE)
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field_fallback_undefined = parse_field(model_fallback_undefined, field_name, NONE)
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descriptor = TranslationFieldDescriptor(
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field,
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fallback_languages=model_fallback_languages,
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fallback_value=field_fallback_value,
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fallback_undefined=field_fallback_undefined)
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setattr(model, field_name, descriptor)
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if isinstance(field, ForeignKey):
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# We need to use a special descriptor so that
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# _id fields on translated ForeignKeys work
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# as expected.
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desc = TranslatedRelationIdDescriptor(field_name, model_fallback_languages)
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setattr(model, field.get_attname(), desc)
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# Set related field names on other model
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if not field.rel.is_hidden():
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other_opts = self._get_options_for_model(field.rel.to)
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other_opts.related = True
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other_opts.related_fields.append(field.related_query_name())
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add_manager(field.rel.to) # Add manager in case of non-registered model
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if isinstance(field, OneToOneField):
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# Fix translated_field caching for SingleRelatedObjectDescriptor
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sro_descriptor = getattr(field.rel.to, field.related.get_accessor_name())
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patch_related_object_descriptor_caching(sro_descriptor)
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def unregister(self, model_or_iterable):
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"""
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Unregisters the given model(s).
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If a model isn't registered, this will raise NotRegistered. If one of
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its subclasses is registered, DescendantRegistered will be raised.
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"""
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if isinstance(model_or_iterable, ModelBase):
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model_or_iterable = [model_or_iterable]
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for model in model_or_iterable:
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# Check if the model is actually registered (``get_options_for_model``
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# throws an exception if it's not).
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self.get_options_for_model(model)
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# Invalidate all submodels options and forget about
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# the model itself.
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for desc, desc_opts in list(self._registry.items()):
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if not issubclass(desc, model):
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continue
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if model != desc and desc_opts.registered:
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# Allowing to unregister a base would necessitate
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# repatching all submodels.
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raise DescendantRegistered(
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'You need to unregister descendant "%s" before'
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' unregistering its base "%s"' %
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(desc.__name__, model.__name__))
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del self._registry[desc]
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def get_registered_models(self, abstract=True):
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"""
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Returns a list of all registered models, or just concrete
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registered models.
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"""
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return [model for (model, opts) in self._registry.items()
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if opts.registered and (not model._meta.abstract or abstract)]
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def _get_options_for_model(self, model, opts_class=None, **options):
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"""
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Returns an instance of translation options with translated fields
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defined for the ``model`` and inherited from superclasses.
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"""
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if model not in self._registry:
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# Create a new type for backwards compatibility.
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opts = type("%sTranslationOptions" % model.__name__,
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(opts_class or TranslationOptions,), options)(model)
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# Fields for translation may be inherited from abstract
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# superclasses, so we need to look at all parents.
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for base in model.__bases__:
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if not hasattr(base, '_meta'):
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# Things without _meta aren't functional models, so they're
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# uninteresting parents.
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continue
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opts.update(self._get_options_for_model(base))
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# Cache options for all models -- we may want to compute options
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# of registered subclasses of unregistered models.
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self._registry[model] = opts
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return self._registry[model]
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def get_options_for_model(self, model):
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"""
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Thin wrapper around ``_get_options_for_model`` to preserve the
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semantic of throwing exception for models not directly registered.
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"""
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opts = self._get_options_for_model(model)
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if not opts.registered and not opts.related:
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raise NotRegistered('The model "%s" is not registered for '
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'translation' % model.__name__)
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return opts
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# This global object represents the singleton translator object
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translator = Translator()
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