models.py

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

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())

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

    freebies = relationship("Freebie", back_populates="company")
    devs = relationship(
        "Dev",
        secondary="freebies",
        primaryjoin="Company.id==Freebie.company_id",
        secondaryjoin="Dev.id==Freebie.dev_id",
        viewonly=True
    )

    def give_freebie(self, dev, item_name, value):
        """Create and give a freebie to a dev from this company."""
        return Freebie(item_name=item_name, value=value, dev=dev, company=self)


class Dev(Base):
    __tablename__ = 'devs'

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

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

    freebies = relationship("Freebie", back_populates="dev")
    companies = relationship(
        "Company",
        secondary="freebies",
        primaryjoin="Dev.id==Freebie.dev_id",
        secondaryjoin="Company.id==Freebie.company_id",
        viewonly=True
    )

    def received_freebie(self, item_name, value, company):
        """Receive a freebie from a company."""
        return Freebie(item_name=item_name, value=value, company=company, dev=self)


class Freebie(Base):
    __tablename__ = "freebies"

    id = Column(Integer, primary_key=True)
    item_name = Column(String(length=255), nullable=False)
    value = Column(Integer, nullable=False)

    company_id = Column(Integer, ForeignKey("companies.id"), nullable=False)
    dev_id = Column(Integer, ForeignKey("devs.id"), nullable=False)

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

    def __repr__(self):
        return f"<Freebie {self.id} - {self.item_name} ({self.value})>"

    def print_details(self):
        """Print details of who owns the freebie and from which company."""
        print(f"{self.dev.name} owns a {self.item_name} from {self.company.name}")