class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    email = Column(String(), nullable=False)
    __table_args__ = (
        Index('users_index_1', "email"),
    )


class Session(Base):
    __tablename__ = 'sessions'
    id = Column(Integer, primary_key=True)
    when_created = Column(DateTime, default=datetime.utcnow)
    user_id = Column(Integer, ForeignKey('users.id'), nullable=False)
    email = Column(String(), nullable=False)

    user = relationship('User')
    __table_args__ = (
        Index('sessions_index_1', "user_id"),
    )


class PageView(Base):
    __tablename__ = 'page_views'
    id = Column(Integer, primary_key=True)
    url = Column(String, nullable=False)
    category = Column(String(20), nullable=True)
    session_id = Column(Integer, ForeignKey('sessions.id'), nullable=False)

    client = relationship('Session')
    __table_args__ = (
        Index('page_views_index_1', "session_id"),
    )