models.py

from sqlalchemy import ForeignKey, Column, Integer, String, MetaData
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.associationproxy import association_proxy

convention = {
    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
}
metadata = MetaData(naming_convention=convention)

Base = declarative_base(metadata=metadata)

class Company(Base):
    __tablename__ = 'companies'

    id = Column(Integer(), primary_key=True)
    name = Column(String())
    founding_year = Column(Integer())

    freebies = relationship('Freebie', back_populates='company')
    devs = association_proxy('freebies', 'dev', creator= lambda dv: Freebie(dev=dv))

    def __repr__(self):
        return f'<Company {self.name}>'

class Dev(Base):
    __tablename__ = 'devs'

    id = Column(Integer(), primary_key=True)
    name= Column(String())

    freebies = relationship('Freebie', back_populates='dev')
    companies = association_proxy('freebies', 'company', creator=lambda cm: Freebie(company=cm))

    def __repr__(self):
        return f'<Dev {self.name}>'
    
class Freebie(Base):
    __tablename__ = 'freebies'

    id = Column(Integer(), primary_key=True)
    name = Column(String())
    company_id = Column(Integer(), ForeignKey('companies.id'))
    dev_id = Column(Integer(), ForeignKey('devs.id'))

    company = relationship('Company', back_populates='freebies')
    dev = relationship('Dev', back_populates='freebies')

    def __init__(self, company=None, dev=None, name=None):
        if company is not None:
            self.company = company
        if dev is not None:
            self.dev = dev
        if name is not None:
            self.name = name

    def __repr__(self):
        return f"<Freebie {self.id}: {self.name} Company_ID: {self.company_id}, Dev_ID: {self.dev_id}>"