I am trying to create a self referencing table in MySql using SqlAlchemy. I get the error

TypeError: Additional arguments should be named <dialectname>_<argument>, got 'ForeignKey'

My code is

from sqlalchemy import (
    create_engine,
    Column,
    Integer,
    String,
    DateTime,
    func,
    Text,
    DECIMAL,
    ForeignKey,
)

# from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, declarative_base, mapped_column, relationship

Base = declarative_base()
class Account(Base):
    __tablename__ = "account"

    id = mapped_column(Integer, primary_key=True)
    name = mapped_column(String(50))
    notes = mapped_column(Text())
    opening_balance = DECIMAL()
    current_balance = DECIMAL()
    parent_id = mapped_column(Integer, ForeignKey="account.id") #error here
    children = relationship("Account")
    created_at = mapped_column(DateTime, default=func.now())
    updated_at = mapped_column(DateTime, default=func.now(), onupdate=func.now())

The error occurs at the line parent_id = ...

Everywhere I looked suggested that the code is correct (and I've looked in a lot of places). Co-Pilot told me to put () around "account.id" but PyCharm told me they were redundant. Either way got the error.

Tried changing mapped_column to Column, same error. Haven't got a clue what to do!

I am trying to create a self referencing table in MySql using SqlAlchemy. I get the error

TypeError: Additional arguments should be named <dialectname>_<argument>, got 'ForeignKey'

My code is

from sqlalchemy import (
    create_engine,
    Column,
    Integer,
    String,
    DateTime,
    func,
    Text,
    DECIMAL,
    ForeignKey,
)

# from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, declarative_base, mapped_column, relationship

Base = declarative_base()
class Account(Base):
    __tablename__ = "account"

    id = mapped_column(Integer, primary_key=True)
    name = mapped_column(String(50))
    notes = mapped_column(Text())
    opening_balance = DECIMAL()
    current_balance = DECIMAL()
    parent_id = mapped_column(Integer, ForeignKey="account.id") #error here
    children = relationship("Account")
    created_at = mapped_column(DateTime, default=func.now())
    updated_at = mapped_column(DateTime, default=func.now(), onupdate=func.now())

The error occurs at the line parent_id = ...

Everywhere I looked suggested that the code is correct (and I've looked in a lot of places). Co-Pilot told me to put () around "account.id" but PyCharm told me they were redundant. Either way got the error.

Tried changing mapped_column to Column, same error. Haven't got a clue what to do!

• python
• mysql
• python-3.x
• sqlalchemy

1 Answer 1

ForeignKey is a function so the (...) need to be instead of the =, your line needs to be:

parent_id = mapped_column(Integer, ForeignKey("account.id"))