# XXX: Check if "gametext" is set correctly everywhere
import collections
+from functools import partial
from sqlalchemy import Column, ForeignKey, MetaData, PrimaryKeyConstraint, Table, UniqueConstraint
from sqlalchemy.ext.declarative import (
backref, compile_mappers, eagerload_all, relation, class_mapper, synonym, mapper,
)
from sqlalchemy.orm.session import Session, object_session
-from sqlalchemy.orm.collections import attribute_mapped_collection
-from sqlalchemy.ext.associationproxy import association_proxy
+from sqlalchemy.orm.interfaces import AttributeExtension
+from sqlalchemy.orm.collections import attribute_mapped_collection, MappedCollection, collection, collection_adapter
+from sqlalchemy.ext.associationproxy import _AssociationDict, association_proxy
from sqlalchemy.sql import and_
-from sqlalchemy.sql.expression import ColumnOperators
+from sqlalchemy.sql.expression import ColumnOperators, bindparam
from sqlalchemy.schema import ColumnDefault
from sqlalchemy.types import *
from inspect import isclass
default_lang = u'en'
+def create_translation_table(_table_name, foreign_class,
+ _language_class=Language, **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.
+TODO give it a __table__ or __init__?
+
+ `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.
+
+ Usage looks like this:
+
+ class Foo(Base): ...
+
+ create_translation_table('foo_bars', Foo,
+ name = Column(...),
+ )
+
+ # Now you can do the following:
+ foo.name
+ foo.name_map['en']
+ foo.foo_bars['en']
+
+ foo.name_map['en'] = "new name"
+ del foo.name_map['en']
+
+ q.options(joinedload(Foo.default_translation))
+ q.options(joinedload(Foo.foo_bars))
+
+ In the above example, the following attributes are added to Foo:
+
+ - `foo_bars`, a relation to the new table. It uses a dict-based collection
+ class, where the keys are language identifiers and the values are rows in
+ the created tables.
+ - `foo_bars_local`, a relation to the row in the new table that matches the
+ current default language.
+
+ Note that these are distinct relations. Even though the former necessarily
+ includes the latter, SQLAlchemy doesn't treat them as linked; loading one
+ will not load the other. Modifying both within the same transaction has
+ undefined behavior.
+
+ For each column provided, the following additional attributes are added to
+ Foo:
+
+ - `(column)_map`, an association proxy onto `foo_bars`.
+ - `(column)`, an association proxy onto `foo_bars_local`.
+
+ Pardon the naming disparity, but the grammar suffers otherwise.
+
+ Modifying these directly is not likely to be a good idea.
+ """
+ # n.b.: _language_class only exists for the sake of tests, which sometimes
+ # 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'),
+ })
+
+ # 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),
+ )
+
+ # Add ye columns
+ # Column objects have a _creation_order attribute in ascending order; use
+ # this to get the (unordered) kwargs sorted correctly
+ kwitems = kwargs.items()
+ kwitems.sort(key=lambda kv: kv[1]._creation_order)
+ for name, column in kwitems:
+ column.name = name
+ table.append_column(column)
+
+ # Construct ye mapper
+ mapper(Translations, table, properties={
+ # TODO change to foreign_id
+ 'object_id': synonym(foreign_key_name),
+ # TODO change this as appropriate
+ 'language': relation(_language_class,
+ primaryjoin=table.c.language_id == _language_class.id,
+ lazy='joined',
+ innerjoin=True),
+ # TODO does this need to join to the original table?
+ })
+
+ # Add full-table relations to the original class
+ # Class.foo_bars
+ class LanguageMapping(MappedCollection):
+ """Baby class that converts a language identifier key into an actual
+ language object, allowing for `foo.bars['en'] = Translations(...)`.
+
+ Needed for per-column association proxies to function as setters.
+ """
+ @collection.internally_instrumented
+ def __setitem__(self, key, value, _sa_initiator=None):
+ if key in self:
+ raise NotImplementedError("Can't replace the whole row, sorry!")
+
+ # Only do this nonsense if the value is a dangling object; if it's
+ # in the db it already has its language_id
+ if not object_session(value):
+ # This took quite some source-diving to find, but it oughta be
+ # the object that actually owns this collection.
+ obj = collection_adapter(self).owner_state.obj()
+ session = object_session(obj)
+ value.language = session.query(_language_class) \
+ .filter_by(identifier=key).one()
+
+ super(LanguageMapping, self).__setitem__(key, value, _sa_initiator)
+
+ setattr(foreign_class, _table_name, relation(Translations,
+ primaryjoin=foreign_class.id == Translations.object_id,
+ #collection_class=attribute_mapped_collection('_language_identifier'),
+ collection_class=partial(LanguageMapping,
+ lambda obj: obj._language_identifier),
+ # TODO
+ lazy='select',
+ ))
+ # Class.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.
+ local_relation_name = _table_name + '_local'
+ setattr(foreign_class, local_relation_name, relation(Translations,
+ primaryjoin=and_(
+ foreign_class.id == Translations.object_id,
+ Translations._language_identifier ==
+ bindparam('_default_language', required=True),
+ ),
+ uselist=False,
+ # TODO MORESO HERE
+ lazy='select',
+ ))
+
+ # Add per-column proxies to the original class
+ for name, column in kwitems:
+ # TODO should these proxies be mutable?
+
+ # Class.(column) -- accessor for the default language's value
+ setattr(foreign_class, name,
+ association_proxy(local_relation_name, name))
+
+ # Class.(column)_map -- accessor for the language dict
+ # Need a custom creator since Translations doesn't have an init, and
+ # these are passed as *args anyway
+ def creator(language_code, value):
+ row = Translations()
+ setattr(row, name, value)
+ return row
+ setattr(foreign_class, name + '_map',
+ association_proxy(_table_name, name, creator=creator))
+
+ # Done
+ return Translations
+
def makeTextTable(foreign_table_class, table_suffix_plural, table_suffix_singular, columns, lazy, Language=Language):
# With "Language", we'd have two language_id. So, rename one to 'lang'
foreign_key_name = foreign_table_class.__singlename__
projects / zzz-pokedex.git / blobdiff