vpsx-fast/app/alchemy/base.py

from sqlalchemy.orm import DeclarativeBase, declared_attr, Mapped, mapped_column, relationship, add_mapped_attribute



def to_snake_case(name: str) -> str:
    return "".join(["_" + i.lower() if i.isupper() else i for i in name]).lstrip("_")



def bidirectional_relationship(cls, foreign_table_cls):
    """Create a bidirectional relationship between two table-classes."""

    column_name = f"{to_snake_case(cls.__name__)}"
    column_name = f"{column_name}es" if column_name.endswith("s") else f"{column_name}s"

    add_mapped_attribute(
        foreign_table_cls,
        column_name,
        relationship(cls,
                     back_populates=foreign_table_cls.__tablename__,
                     cascade="all, delete-orphan"
                     )
    )

    return relationship(foreign_table_cls.__name__, back_populates=column_name)


class Base(DeclarativeBase):
    __abstract__ = True

    id: Mapped[int] = mapped_column(primary_key=True, sort_order=-1000000)

    # noinspection PyMethodParameters
    @declared_attr.directive
    def __tablename__(cls) -> str:
        """Default table name in Database is derived from Class Name"""
        return to_snake_case(cls.__name__)


# noinspection PyPep8Naming