NoForeignKeysError with polymorphism and schemas

[ThiefMaster]

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql:///test'
db = SQLAlchemy(app)


class Item(db.Model):
    __tablename__ = 'items'
    __table_args__ = {'schema': 'foo'}  # this causes the error
    __mapper_args__ = {'polymorphic_on': 'type', 'polymorphic_identity': None}

    id = db.Column(db.Integer, primary_key=True)
    type = db.Column(db.Integer, nullable=False)
    parent_id = db.Column(db.ForeignKey('foo.items.id'), index=True, nullable=True)
    children = db.relationship('Item', backref=db.backref('parent', remote_side=[id]))


class SubItem(Item):
    __mapper_args__ = {
        'polymorphic_identity': 1
    }

traceback:

Traceback (most recent call last):
  File "flasksatest.py", line 21, in <module>
    class SubItem(Item):
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/flask_sqlalchemy/__init__.py", line 602, in __init__
    DeclarativeMeta.__init__(self, name, bases, d)
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/api.py", line 64, in __init__
    _as_declarative(cls, classname, cls.__dict__)
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py", line 88, in _as_declarative
    _MapperConfig.setup_mapping(cls, classname, dict_)
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py", line 103, in setup_mapping
    cfg_cls(cls_, classname, dict_)
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py", line 135, in __init__
    self._early_mapping()
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py", line 138, in _early_mapping
    self.map()
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py", line 534, in map
    **self.mapper_args
  File "<string>", line 2, in mapper
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py", line 671, in __init__
    self._configure_inheritance()
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py", line 978, in _configure_inheritance
    self.local_table)
  File "<string>", line 2, in join_condition
  File "/home/adrian/dev/indico/env/lib/python2.7/site-packages/sqlalchemy/sql/selectable.py", line 979, in _join_condition
    (a.description, b.description, hint))
sqlalchemy.exc.NoForeignKeysError: Can't find any foreign key relationships between 'items' and 'items'.

It works fine if I do not use a custom schema.

[davidism]

I'm not really familiar with Postgres schemas, and I'm not sure a test for this would work with the SQLite backend. Would you verify that #541 fixes this?

[davidism]

Have confirmation from Thief that this will be fixed by the tablename patch.

[halfdan]

I'm actually still seeing this error in the latest version.

Same setup only difference is: __mapper_args__ = {"polymorphic_identity": "geo_item", "concrete": True}