CODEWITHSUNDEEP
pythonsqlalchemyforeign-keys
ExperimentsWithCode
ExperimentsWithCode

Reputation: 1184

Sqlalchemy, trouble linking multiple columns. Foreign key Error.

For some reason I get a foreign key error when a I try to link a certain aspect of my Actions table with my contacts table. The error I get is:

sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join condition between parent/child tables on relationship Contacts.actions - there are multiple foreign key paths linking the tables. Specify the 'foreign_keys' argument, providing a list of those columns which should be counted as containing a foreign key reference to the parent table.

I need help understanding why the already linked table doesnt apply to the second attribute. (see line surrounded by comments in code below)

My Declarative Code:

Base = declarative_base()

class Users(Base):
    __tablename__ = 'users'
    # Here we define columns for the table person
    # Notice that each column is also a normal Python instance attribute.
    id = Column(Integer, primary_key=True)
    username = Column(String(30), nullable=False)
    first_name =  Column(String(20), nullable=False)
    last_name =  Column(String(20), nullable=False)
    email =  Column(String(40), nullable=False)
    phone =  Column(String(10), nullable=False)
    #default_duration =  Column(Integer(2))

class Actions(Base):
    __tablename__ = 'actions'
    id = Column(Integer, primary_key=True)
    action = Column(String(15), nullable=False)
    message =  Column(String(140), nullable=False)
    duration =  Column(Integer(2), nullable=False)



class Contacts(Base):
    __tablename__ = 'contacts'
    # Here we define columns for the table address.
    # Notice that each column is also a normal Python instance attribute.
    id = Column(Integer, primary_key=True)
    contact_name = Column(String(30), nullable=False)
    time_of_last_message = Column(String(40))
    message_log = Column(String(450))
    users_id = Column(Integer, ForeignKey('users.id'), nullable=False)
    users = relationship(Users)

     ##############################
    #### If this line is commented it out, it works
    #### But If it is present I get the error
    actions_action = Column(String, ForeignKey('actions.action'))
    ####
    ###############################

    actions_id =  Column(Integer, ForeignKey('actions.id'))
    actions = relationship(Actions)

Upvotes: 0

Views: 1306

Answers (1)

univerio
univerio

Reputation: 20548

Because, as the error message says, you have multiple foreign keys between Contacts and Actions, namely actions_id and actions_action, so it doesn't know which one you want to use for the relationship actions. You can fix it by specifying (again, as the error message suggests) foreign_keys:

actions = relationship(Actions, foreign_keys=actions_id)

This fixes the error, but a better question would be why you would need actions_action in addition to actions_id?

Upvotes: 1

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