def add_select_related(self, fields):
"""
If in fields is related_field for translations, will be replaced by fields in proper languages.
"""
new_fields = []
extra_select = {}
opts = self.model._meta
trans_opts = opts.translation_model._meta
# TODO: fix this
#related_name = trans_opts.related_name
related_name = 'translations'
translation_fields = [f.name for f in trans_opts.fields if f.name not in ('master', 'language_code')]
for field in fields:
# usual select_related
if not field.startswith(related_name):
new_fields.append(field)
continue
# get language
if field == related_name:
language_code = get_active()
else:
field_and_lang = field.rsplit('_', 1)
# Coincidental field name might occur if language_code is not correct, do not do anything as
# select_related does not raise errors if used with incorrect fields
if len(field_and_lang) != 2 or field_and_lang[1] not in get_all():
new_fields.append(field)
continue
field, language_code = field_and_lang
# This is main code of this method, build extra_select that might be used by fill_translation_cache
for trans_field in translation_fields:
extra_select[get_field_alias(trans_field, language_code)] = '%s.%s' % (
get_table_alias(trans_opts.db_table, language_code),
connection.ops.quote_name(trans_field)
)
# XXX: this is not safe if translation model has no fields, can it happen??
# join translatable model (original) table if not joined yet
alias = self.get_initial_alias()
# join translation table if not joined yet
translation_fields.remove(trans_opts.pk.name)
self.setup_joins(
['%s_%s' % (translation_fields[0], language_code)], # any translated_field
opts,
alias,
True,
can_reuse = set([alias])
)
if extra_select:
self.add_extra(extra_select, None, None, None, None, None)
super(MultilingualQuery, self).add_select_related(new_fields)
def _fill_translation_cache(self, language_code):
"""
Fill the translation cache using information from query.extra_fields if any.
"""
# This can not be called in post_init because the extra fields are
# assigned by QuerySet.iterator after model initialization.
# unsaved instances does not have translations
if not self.pk:
return
# skip if we already has translation, or we know there is not one
if cache_state():
self._translation_cache = cache.get(
"ml_cache_%s_%s" % (self._meta.db_table, self.pk), self._translation_cache
)
if self._translation_cache.has_key(language_code):
return
c_trans_model = self._meta.translation_model
# see if translation was in the query
# WARNING: This must fail if we do not have all fields in query
translation_data = {}
for field_name in [f.attname for f in c_trans_model._meta.fields]:
# We know values of language_code and master_id, so we does not expect them to be in query
if field_name in ("language_code", "master_id"):
continue
try:
translation_data[field_name] = getattr(self, get_field_alias(field_name, language_code))
except AttributeError:
# if any field is missing we can not store data in translation cache
# and we need to use direct query
translation_data = None
break
if translation_data is not None:
translation = c_trans_model(language_code=language_code, master=self, **translation_data)
self._translation_cache[language_code] = translation
else:
# If we do not have translation (e.g. was not part of query)
# we will try direct query to load it
try:
# TODO, XXX: get correct related_name instead of 'translations' !!!
self._translation_cache[language_code] = self.translations.get(language_code=language_code)
except c_trans_model.DoesNotExist:
# translation does not exist, we store None to avoid repetitive calls of this code
self._translation_cache[language_code] = None
cache.set("ml_cache_%s_%s" % (self._meta.db_table, self.pk), self._translation_cache, 3600)
def _get_translation_from_select_related(self, language_code):
c_trans_model = self._meta.translation_model
# see if translation was in the query
# WARNING: This must fail if we do not have all fields in query
translation_data = {}
for field_name in [f.attname for f in c_trans_model._meta.fields]:
# We know values of language_code and master_id, so we does not expect them to be in query
if field_name in ('language_code', 'master_id'):
continue
try:
translation_data[field_name] = getattr(self, get_field_alias(field_name, language_code))
except AttributeError:
# if any field is missing we can not store data in translation cache
# and we need to use direct query
translation_data = None
break
if translation_data is not None:
return c_trans_model(language_code=language_code, master=self, **translation_data)
else:
return None
