belgie-alchemy 0.1.0a4

SQLAlchemy building blocks for Belgie

belgie-alchemy

SQLAlchemy 2.0 building blocks for database models.

Overview

belgie-alchemy provides opinionated defaults and utilities for SQLAlchemy:

• Base: Declarative base with dataclass mapping and sensible defaults
• Mixins: PrimaryKeyMixin (UUID), TimestampMixin (created/updated/deleted timestamps)
• Types: DateTimeUTC (timezone-aware datetimes), Scopes (dialect-specific array/JSON storage)

This module provides building blocks only - you define your own models.

Quick Start

from datetime import datetime
from belgie_alchemy import Base, PrimaryKeyMixin, TimestampMixin, DateTimeUTC
from sqlalchemy.orm import Mapped, mapped_column

class Article(Base, PrimaryKeyMixin, TimestampMixin):
    __tablename__ = "articles"

    title: Mapped[str]
    published_at: Mapped[datetime] = mapped_column(DateTimeUTC)

This gives you:

• UUID primary key with server-side generation
• Automatic created_at, updated_at, deleted_at timestamps
• Timezone-aware datetime handling
• Dataclass-style __init__, __repr__, __eq__

Building Blocks

Base

Declarative base with dataclass mapping enabled:

from belgie_alchemy import Base
from sqlalchemy.orm import Mapped, mapped_column

class MyModel(Base):
    __tablename__ = "my_models"

    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str]

# Dataclass-style instantiation
model = MyModel(id=1, name="example")

Features:

• Consistent naming conventions for constraints
• Automatic type annotation mapping (datetime → DateTimeUTC)
• Dataclass mapping with kw_only=True, repr=True, eq=True

Mixins

PrimaryKeyMixin

Adds a UUID primary key with server-side generation:

from belgie_alchemy import Base, PrimaryKeyMixin

class MyModel(Base, PrimaryKeyMixin):
    __tablename__ = "my_models"
    # Automatically includes: id: Mapped[UUID]

The id field:

• Type: UUID
• Server-generated using gen_random_uuid()
• Indexed and unique
• Primary key

TimestampMixin

Adds automatic timestamp tracking:

from belgie_alchemy import Base, TimestampMixin

class MyModel(Base, TimestampMixin):
    __tablename__ = "my_models"
    # Automatically includes:
    # - created_at: Mapped[datetime]
    # - updated_at: Mapped[datetime] (auto-updates on changes)
    # - deleted_at: Mapped[datetime | None]

Features:

• created_at set automatically on insert
• updated_at auto-updates on row changes
• deleted_at for soft deletion
• mark_deleted() method to set deleted_at

Types

DateTimeUTC

Timezone-aware datetime storage:

from datetime import datetime
from belgie_alchemy import Base, DateTimeUTC
from sqlalchemy.orm import Mapped, mapped_column

class Event(Base):
    __tablename__ = "events"

    id: Mapped[int] = mapped_column(primary_key=True)
    happened_at: Mapped[datetime] = mapped_column(DateTimeUTC)

Features:

• Automatically converts naive datetimes to UTC
• Preserves timezone-aware datetimes
• Always returns UTC-aware datetimes from database
• Works with PostgreSQL, SQLite, MySQL

Scopes

Dialect-specific array storage for permission scopes:

from enum import StrEnum
from belgie_alchemy import Base, Scopes
from sqlalchemy.orm import Mapped, mapped_column

class User(Base):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(primary_key=True)
    # Option 1: Simple string array (works everywhere)
    scopes: Mapped[list[str] | None] = mapped_column(Scopes, default=None)

Features:

• PostgreSQL: Uses native ARRAY(String) type
• SQLite/MySQL: Uses JSON storage
• Automatically converts StrEnum values to strings
• Handles None values correctly

For PostgreSQL with application-specific enum types, you can override:

from enum import StrEnum
from sqlalchemy import ARRAY
from sqlalchemy.dialects.postgresql import ENUM

class AppScope(StrEnum):
    READ = "resource:read"
    WRITE = "resource:write"
    ADMIN = "admin"

class User(Base):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(primary_key=True)
    # Option 2: PostgreSQL native ENUM array (type-safe)
    scopes: Mapped[list[AppScope] | None] = mapped_column(
        ARRAY(ENUM(AppScope, name="app_scope", create_type=True)),
        default=None,
    )

Complete Example: Auth Models

See examples/alchemy/auth_models.py for a complete reference implementation of authentication models:

• User - with email, verification, and scopes
• Account - OAuth provider linkage
• Session - user session management
• OAuthState - OAuth flow state

These are templates - copy them to your project and customize as needed.

Example structure:

from datetime import datetime
from uuid import UUID
from sqlalchemy import ForeignKey
from sqlalchemy.orm import Mapped, mapped_column, relationship
from belgie_alchemy import Base, PrimaryKeyMixin, TimestampMixin, DateTimeUTC, Scopes

class User(Base, PrimaryKeyMixin, TimestampMixin):
    __tablename__ = "users"

    email: Mapped[str] = mapped_column(unique=True, index=True)
    email_verified: Mapped[bool] = mapped_column(default=False)
    scopes: Mapped[list[str] | None] = mapped_column(Scopes, default=None)

    accounts: Mapped[list["Account"]] = relationship(
        back_populates="user",
        cascade="all, delete-orphan",
        init=False,
    )

class Account(Base, PrimaryKeyMixin, TimestampMixin):
    __tablename__ = "accounts"

    user_id: Mapped[UUID] = mapped_column(
        ForeignKey("users.id", ondelete="cascade"),
        nullable=False,
    )
    provider: Mapped[str]
    provider_account_id: Mapped[str]

    user: Mapped[User] = relationship(
        back_populates="accounts",
        lazy="selectin",
        init=False,
    )

Design Principles

1. Building blocks, not frameworks - You own your models completely
2. Sensible defaults - UTC datetimes, UUIDs, timestamps by default
3. Dataclass-friendly - Clean instantiation and repr
4. Dialect-aware - Use the best type for each database
5. Minimal magic - Clear, explicit behavior

Migration from impl/auth.py

If you previously imported models from belgie_alchemy.impl.auth:

Before:

from belgie_alchemy.impl.auth import User, Account, Session, OAuthState

After:

# Copy models from examples/alchemy/auth_models.py to your project
# Then import from your own code:
from myapp.models import User, Account, Session, OAuthState

This gives you full control to customize the models for your application.