Hi Michael, thanks for the prompt reply.
However, When I tried according to the suggestion, I get this error:
45 class Groups(ModelBase, VersionColumnMixin):
46 domain_id = sa.Column(sa.String(36),
DefaultClause('default'), nullable=False)
47 description = sa.Column(sa.Text)
48 date_created = sa.Column(sa.DateTime)
49 group_name = sa.Column(sa.String(64), nullable=False,
index=True)
50 child_groups = relationship('Groups',
secondary=groups_and_groups_assoc_table,
51 primaryjoin=
*"Groups.id==groups_and_groups_assoc_table.c.parent_group_id"*,
52 secondaryjoin=
*"Groups.id==groups_and_groups_assoc_table.c.child_group_id"*,
53 backref='parent_groups')
54 __table_args__ = (sa.UniqueConstraint('domain_id',
'group_name'),)
Traceback (most recent call last):
File "./selfref4.py", line 67, in <module>
g1 = Groups(description='1234', group_name='group1')
File "<string>", line 2, in __init__
File
"/usr/lib64/python2.6/site-packages/sqlalchemy/orm/instrumentation.py",
line 322, in _new_state_if_none
state = self._state_constructor(instance, self)
File "/usr/lib64/python2.6/site-packages/sqlalchemy/util/langhelpers.py",
line 689, in __get__
obj.__dict__[self.__name__] = result = self.fget(obj)
...
...File
"/usr/lib64/python2.6/site-packages/sqlalchemy/ext/declarative/clsregistry.py",
line 275, in __call__
(self.prop.parent, self.arg, n.args[0], self.cls)
*sqlalchemy.exc.InvalidRequestError:* When initializing mapper
Mapper|Groups|groups, expression
'Groups.id==groups_and_groups_assoc_table.c.parent_group_id' failed to
locate a name ("name 'groups_and_groups_assoc_table' is not defined"). If
this is a class name, consider adding this relationship() to the <class
'__main__.Groups'> class after both dependent classes have been defined.
On Tuesday, March 11, 2014 2:10:52 PM UTC-7, Michael Bayer wrote:
>
>
> On Mar 11, 2014, at 3:50 PM, Bala <[email protected] <javascript:>> wrote:
>
> 45 class Groups(ModelBase, VersionColumnMixin):
> 46 *id = sa.Column('id', sa.Integer, Sequence('id_seq'),
> primary_key=True)*
> 47 domain_id = sa.Column(sa.String(36),
> DefaultClause('default'), nullable=False)
> 48 description = sa.Column(sa.Text)
> 49 date_created = sa.Column(sa.DateTime)
> 50 group_name = sa.Column(sa.String(64), nullable=False,
> index=True)
> 51 child_groups = relationship('Groups',
> secondary=groups_and_groups_assoc_table,
> 52
> primaryjoin=id==groups_and_groups_assoc_table.c.parent_group_id,
> 53
> secondaryjoin=id==groups_and_groups_assoc_table.c.child_group_id,
> 54 backref='parent_groups’)
>
>
> here, when the definition of the Python identifier “id” within the Groups
> class definition is removed, it is no longer valid to refer to the word
> “id” within the “primaryjoin” and “secondaryjoin” conditions, as “id” is
> not defined. The reason it seems to be defined is that it is resolving to
> the Python built in function “id”. Unfortunately the exception message
> isn’t being too smart here, interpreting “id” as just another literal value
> like the number “3” so you don’t see it, it wouldn’t be a bad idea for SQLA
> to detect this kind of thing but that is actually somewhat difficult as it
> is valid for an expression to refer to a callable.
>
> Since “id” is not yet defined within the class body of Groups you need to
> specify conditions using a string:
>
> class Groups(ModelBase, VersionColumnMixin):
> domain_id = sa.Column(sa.String(36), DefaultClause('default'),
> nullable=False)
> description = sa.Column(sa.Text)
> date_created = sa.Column(sa.DateTime)
> group_name = sa.Column(sa.String(64), nullable=False, index=True)
> child_groups = relationship('Groups',
> secondary=groups_and_groups_assoc_table,
>
> primaryjoin="Groups.id==groups_and_groups.c.parent_group_id",
>
> secondaryjoin="Groups.id==groups_and_groups.c.child_group_id",
> backref='parent_groups')
> __table_args__ = (sa.UniqueConstraint('domain_id', 'group_name'),)
>
>
> i’m updating the document at
> http://docs.sqlalchemy.org/en/rel_0_9/orm/relationships.html#self-referential-many-to-many-relationshipto
> include this form now.
>
>
>
>
>
>
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