app/models/base.py

"""
Base Model Classes
Mixins and base classes for all SQLAlchemy models
"""

import uuid
from datetime import datetime

from sqlalchemy import Column, DateTime
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.ext.declarative import declarative_base, declared_attr

Base = declarative_base()


class UUIDMixin:
    """Mixin that adds a UUID primary key"""

    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4, index=True)


class TimestampMixin:
    """Mixin that adds created_at and updated_at timestamps"""

    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)

    updated_at = Column(
        DateTime, default=datetime.utcnow, onupdate=datetime.utcnow, nullable=True
    )


class TableNameMixin:
    """Mixin that auto-generates table name from class name"""

    @declared_attr
    def __tablename__(cls):
        # Convert CamelCase to snake_case
        name = cls.__name__
        return "".join(["_" + c.lower() if c.isupper() else c for c in name]).lstrip(
            "_"
        )