获取sqlalchemy视图反射在flask-sqlalchemy中工作

Question

Flask-SQLAlchemy's support of SQLAlchemy's reflection doesn't seem to be working quite right for me. I have a view my_view that I want to reflect on via autoload .

But I want my_view to be a rich object and have various functions so I want my_view to subclass db.Model . I want it to pretty much work like any other db model that is not a view.

I do it like this:

class MyView(db.Model):
    __tablename__ = 'my_view',
    __table_args__ = (
        db.UniqueConstraint('id', 'start_date'),
        {
            'autoload': True,
            'autoload_with': db.engine
        }
    )

    ...my column defs...

    ...extra functionality...

But during app bootstrap time I get an error:

<snip>
File "env/lib/python3.4/site-packages/sqlalchemy/dialects/postgresql/base.py", line 2325, in get_columns
info_cache=kw.get('info_cache'))
File "<string>", line 2, in get_table_oid
File "env/lib/python3.4/site-packages/sqlalchemy/engine/reflection.py", line 54, in cache
ret = fn(self, con, *args, **kw)
File "env/lib/python3.4/site-packages/sqlalchemy/dialects/postgresql/base.py", line 2223, in get_table_oid
    raise exc.NoSuchTableError(table_name)
sqlalchemy.exc.NoSuchTableError: ('my_view',)

However, if I use db.Table instead of db.Model it works:

MyView = db.Table(
    'my_view',
    db.metadata,
    ...my column defs...
    autoload=True,
    autoload_with=db.engine
)

I really want to have an object and use db.Model though, so I can implement __eq__() and __json__() and be able to do things like:

my_view_rows = session.query(MyView)\
                      .order_by(MyView.column_a)\
                      .all() 

Anyone know why the db.Model version of my code is not working? What do I need to do to get it working?

Answer 1

Using __table__ instead of __tablename__ and __table_args__ works.

class MyView(db.Model):
    __table__ = db.Table(
        'my_view', db.metadata,
        db.Column('other_table_id', db.Integer, db.ForeignKey('other_table.id'), primary_key=True),
        ...other column defs...
        autoload=True,
        autoload_with=db.engine
    )

    other_table = db.relationship('OtherTable')