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
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