from sqlalchemy.ext.associationproxy import association_proxy
from sqlalchemy.orm import aliased, compile_mappers, mapper, relationship, synonym
from sqlalchemy.orm.collections import attribute_mapped_collection
+from sqlalchemy.orm.scoping import ScopedSession
from sqlalchemy.orm.session import Session, object_session
from sqlalchemy.schema import Column, ForeignKey, Table
from sqlalchemy.sql.expression import and_, bindparam, select
from sqlalchemy.types import Integer
def create_translation_table(_table_name, foreign_class, relation_name,
- language_class, **kwargs):
+ language_class, relation_lazy='select', **kwargs):
"""Creates a table that represents some kind of data attached to the given
foreign class, but translated across several languages. Returns the new
table's mapped class. It won't be declarative, but it will have a
`foreign_class` must have a `__singlename__`, currently only used to create
the name of the foreign key column.
-TODO remove this requirement
Also supports the notion of a default language, which is attached to the
session. This is English by default, for historical and practical reasons.
# want to create tables entirely separate from the pokedex metadata
foreign_key_name = foreign_class.__singlename__ + '_id'
- # A foreign key "language_id" will clash with the language_id we naturally
- # put in every table. Rename it something else
- if foreign_key_name == 'language_id':
- # TODO change language_id below instead and rename this
- foreign_key_name = 'lang_id'
Translations = type(_table_name, (object,), {
- '_language_identifier': association_proxy('language', 'identifier'),
+ '_language_identifier': association_proxy('local_language', 'identifier'),
})
# Create the table object
table = Table(_table_name, foreign_class.__table__.metadata,
Column(foreign_key_name, Integer, ForeignKey(foreign_class.id),
- primary_key=True, nullable=False),
- Column('language_id', Integer, ForeignKey(language_class.id),
- primary_key=True, nullable=False),
+ primary_key=True, nullable=False,
+ info=dict(description="ID of the %s these texts relate to" % foreign_class.__singlename__)),
+ Column('local_language_id', Integer, ForeignKey(language_class.id),
+ primary_key=True, nullable=False,
+ info=dict(description="Language these texts are in")),
)
Translations.__table__ = table
# Construct ye mapper
mapper(Translations, table, properties={
- # TODO change to foreign_id
- 'object_id': synonym(foreign_key_name),
- # TODO change this as appropriate
- 'language': relationship(language_class,
- primaryjoin=table.c.language_id == language_class.id,
- lazy='joined',
- innerjoin=True),
- # TODO does this need to join to the original table?
+ 'foreign_id': synonym(foreign_key_name),
+ 'local_language': relationship(language_class,
+ primaryjoin=table.c.local_language_id == language_class.id,
+ innerjoin=True,
+ lazy='joined'),
})
# Add full-table relations to the original class
setattr(foreign_class, relation_name + '_table', Translations)
# Foo.bars
setattr(foreign_class, relation_name, relationship(Translations,
- primaryjoin=foreign_class.id == Translations.object_id,
- collection_class=attribute_mapped_collection('language'),
- # TODO
- lazy='select',
+ primaryjoin=foreign_class.id == Translations.foreign_id,
+ collection_class=attribute_mapped_collection('local_language'),
))
# Foo.bars_local
# This is a bit clever; it uses bindparam() to make the join clause
- # modifiable on the fly. db sessions know the current language identifier
- # populates the bindparam. The manual alias and join are (a) to make the
- # condition nice (sqla prefers an EXISTS) and to make the columns play nice
- # when foreign_class == language_class.
+ # modifiable on the fly. db sessions know the current language and
+ # populate the bindparam.
+ # The 'dummy' value is to trick SQLA; without it, SQLA thinks this
+ # bindparam is just its own auto-generated clause and everything gets
+ # fucked up.
local_relation_name = relation_name + '_local'
- language_class_a = aliased(language_class)
setattr(foreign_class, local_relation_name, relationship(Translations,
primaryjoin=and_(
- foreign_class.id == Translations.object_id,
- Translations.language_id == select(
- [language_class_a.id],
- language_class_a.identifier ==
- bindparam('_default_language', required=True),
- ),
+ Translations.foreign_id == foreign_class.id,
+ Translations.local_language_id == bindparam('_default_language_id',
+ value='dummy', type_=Integer, required=True),
),
+ foreign_keys=[Translations.foreign_id, Translations.local_language_id],
uselist=False,
- # TODO MORESO HERE
- lazy='select',
+ #innerjoin=True,
+ lazy=relation_lazy,
))
# Add per-column proxies to the original class
# these are passed as *args anyway
def creator(language, value):
row = Translations()
- row.language = language
+ row.local_language = language
setattr(row, name, value)
return row
setattr(foreign_class, name + '_map',
association_proxy(relation_name, name, creator=creator))
+ # Add to the list of translation classes
+ foreign_class.translation_classes.append(Translations)
+
# Done
return Translations
class MultilangSession(Session):
- """A tiny Session subclass that adds support for a default language."""
- default_language = 'en'
+ """A tiny Session subclass that adds support for a default language.
+
+ Caller will need to assign something to `default_language` before this will
+ actually work.
+ """
+ _default_language_id = 0 # Better fill this in, caller
+
+ def __init__(self, *args, **kwargs):
+ self.language_class = kwargs.pop('language_class')
+ super(MultilangSession, self).__init__(*args, **kwargs)
+
+ @property
+ def default_language(self):
+ return self.query(self.language_class) \
+ .filter_by(id=self._default_language_id) \
+ .one()
+
+ @default_language.setter
+ def default_language(self, new):
+ self._default_language_id = new.id
+
+ @default_language.deleter
+ def default_language(self):
+ try:
+ del self._default_language_id
+ except AttributeError:
+ pass
def execute(self, clause, params=None, *args, **kwargs):
if not params:
params = {}
- params.setdefault('_default_language', self.default_language)
+ params.setdefault('_default_language_id', self._default_language_id)
return super(MultilangSession, self).execute(
clause, params, *args, **kwargs)
+
+class MultilangScopedSession(ScopedSession):
+ """Dispatches language selection to the attached Session."""
+
+ @property
+ def default_language(self):
+ return self.registry().default_language
+
+ @default_language.setter
+ def default_language(self, new):
+ self.registry().default_language = new
projects / zzz-pokedex.git / blobdiff