ForeignKey accepts the name of the table in its string argument, hence the
error "could not find *table* 'Character'", so that would be
ForeignKey('characters.id').
Additionally, since there is more than one way to join "characters" to
"sympathylists", you'll need primaryjoin on each relationship.
Here's all that:
class Character(Base):
__tablename__ = "characters"
id = Column(Integer, primary_key=True)
name = Column(Unicode, nullable=False)
sex = Column(Enum("male", "female"))
sympathy_list = relationship("Sympathylist", backref="loved_by",
primaryjoin="Character.id==Sympathylist.character_id")
class Sympathylist(Base):
__tablename__ = "sympathylists"
character_id = Column(Integer, ForeignKey("characters.id"), nullable=False,
primary_key=True)
sympathic_id = Column(Integer, ForeignKey("characters.id"), nullable=False,
primary_key=True)
order = Column(Integer, nullable=False)
sympathy_list = relationship("Character", backref="loves_me",
primaryjoin="Character.id==Sympathylist.sympathic_id")
On Aug 31, 2011, at 10:55 AM, bika wrote:
> Hi,
>
> I could someone help me in putting together a self-referencing association
> object?
>
> The docs write about self-referencing many2many and association objects
> separately, but I simply can't figure out how merge the two techniques (for
> example one uses declarative, the other doesn't)
>
> This is what I've tried:
>
> class Character(Base):
> __tablename__ = "characters"
>
> id = Column(Integer, primary_key=True)
> name = Column(Unicode, nullable=False)
> sex = Column(Enum("male", "female"))
>
> sympathy_list = relationship("Sympathylist",
> backref="loved_by")
>
> class Sympathylist(Base):
> __tablename__ = "sympathylists"
>
> character_id = Column(Integer, ForeignKey("Character.id"), nullable=False,
> primary_key=True)
> sympathic_id = Column(Integer, ForeignKey("Character.id"), nullable=False,
> primary_key=True)
> order = Column(Integer, nullable=False)
>
> sympathy_list = relationship("Character", backref="loves_me")
>
> But this gives
>
> Foreign key associated with column 'sympathylists.character_id' could not
> find table 'Character' with which to generate a foreign key to target column
> 'id'
>
> I've tried the non-declarative way too, and thought to add a mapping to the
> table later.
>
> sympathylist = Table("sympahtylists", Base.metadata,
> Column("character_id", Integer, ForeignKey("characters.id"),
> nullable=False,
> primary_key=True),
> Column("sympathic_id", Integer, ForeignKey("characters.id"),
> nullable=False,
> primary_key=True),
> Column("order", Integer, nullable=False))
>
> class Character(Base):
> __tablename__ = "characters"
>
> id = Column(Integer, primary_key=True)
> name = Column(Unicode, nullable=False)
> sex = Column(Enum("male", "female"))
> # sympathy_ids = Column(Integer, ForeignKey("Character.id"))
>
> sympathy_list = relationship("Character",
> secondary=sympathylist,
> primaryjoin=sympathylist.c.character_id,
> secondaryjoin=sympathylist.c.sympathic_id,
> backref="loved_by")
>
> but this fails with
>
> sqlalchemy.exc.ArgumentError: Could not determine relationship direction for
> primaryjoin condition 'sympahtylists.character_id', on relationship
> Character.sympathy_list. Ensure that the referencing Column objects have a
> ForeignKey present, or are otherwise part of a ForeignKeyConstraint on their
> parent Table, or specify the foreign_keys parameter to this relationship.
>
> thanks for any help
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To post to this group, send email to [email protected].
> To unsubscribe from this group, send email to
> [email protected].
> For more options, visit this group at
> http://groups.google.com/group/sqlalchemy?hl=en.
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
