X-Git-Url: http://git.veekun.com/zzz-pokedex.git/blobdiff_plain/a227e7adcc899aac9b7c0cb4ff2d4c7428349fce..c87f91105dbce6befb0d4b68c1d6b9bb2a69e805:/pokedex/db/multilang.py

diff --git a/pokedex/db/multilang.py b/pokedex/db/multilang.py
index 8ac1bfc..d58f6df 100644
--- a/pokedex/db/multilang.py
+++ b/pokedex/db/multilang.py
@@ -3,13 +3,14 @@ from functools import partial
 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
@@ -76,9 +77,11 @@ def create_translation_table(_table_name, foreign_class, relation_name,
     # 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),
+            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),
+            primary_key=True, nullable=False,
+            info=dict(description="Language these texts are in")),
     )
     Translations.__table__ = table
 
@@ -96,8 +99,8 @@ def create_translation_table(_table_name, foreign_class, relation_name,
         'foreign_id': synonym(foreign_key_name),
         'local_language': relationship(language_class,
             primaryjoin=table.c.local_language_id == language_class.id,
-            lazy='joined',
-            innerjoin=True),
+            innerjoin=True,
+            lazy='joined'),
     })
 
     # Add full-table relations to the original class
@@ -107,29 +110,25 @@ def create_translation_table(_table_name, foreign_class, relation_name,
     setattr(foreign_class, relation_name, relationship(Translations,
         primaryjoin=foreign_class.id == Translations.foreign_id,
         collection_class=attribute_mapped_collection('local_language'),
-        # TODO
-        lazy='select',
     ))
     # 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.foreign_id,
-            Translations.local_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
@@ -149,16 +148,55 @@ def create_translation_table(_table_name, foreign_class, relation_name,
         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