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Models

Added in v2.0

Reusable SQLAlchemy 2.0 mixins for common column patterns, designed to be composed freely on any DeclarativeBase model.

Overview

The models module provides mixins that each add a single, well-defined column behaviour. They work with standard SQLAlchemy 2.0 declarative syntax and are fully compatible with AsyncSession.

from fastapi_toolsets.models import UUIDMixin, TimestampMixin

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

    title: Mapped[str]
    content: Mapped[str]

All timestamp columns are timezone-aware (TIMESTAMPTZ). All defaults are server-side (clock_timestamp()), so they are also applied when inserting rows via raw SQL outside the ORM.

Mixins

UUIDMixin

Adds a id: UUID primary key generated server-side by PostgreSQL using gen_random_uuid(). The value is retrieved via RETURNING after insert, so it is available on the Python object immediately after flush().

Requires PostgreSQL 13+

from fastapi_toolsets.models import UUIDMixin

class User(Base, UUIDMixin):
    __tablename__ = "users"

    username: Mapped[str]

# id is None before flush
user = User(username="alice")
session.add(user)
await session.flush()
print(user.id)  # UUID('...')

UUIDv7Mixin

Added in v2.3

Adds a id: UUID primary key generated server-side by PostgreSQL using uuidv7(). It's a time-ordered UUID format that encodes a millisecond-precision timestamp in the most significant bits, making it naturally sortable and index-friendly.

Requires PostgreSQL 18+

from fastapi_toolsets.models import UUIDv7Mixin

class Event(Base, UUIDv7Mixin):
    __tablename__ = "events"

    name: Mapped[str]

# id is None before flush
event = Event(name="user.signup")
session.add(event)
await session.flush()
print(event.id)  # UUID('019...')

CreatedAtMixin

Adds a created_at: datetime column set to clock_timestamp() on insert. The column has no onupdate hook — it is intentionally immutable after the row is created.

from fastapi_toolsets.models import UUIDMixin, CreatedAtMixin

class Order(Base, UUIDMixin, CreatedAtMixin):
    __tablename__ = "orders"

    total: Mapped[float]

UpdatedAtMixin

Adds an updated_at: datetime column set to clock_timestamp() on insert and automatically updated to clock_timestamp() on every ORM-level update (via SQLAlchemy's onupdate hook).

from fastapi_toolsets.models import UUIDMixin, UpdatedAtMixin

class Post(Base, UUIDMixin, UpdatedAtMixin):
    __tablename__ = "posts"

    title: Mapped[str]

post = Post(title="Hello")
await session.flush()
await session.refresh(post)

post.title = "Hello World"
await session.flush()
await session.refresh(post)
print(post.updated_at)

Note

updated_at is updated by SQLAlchemy at ORM flush time. If you update rows via raw SQL (e.g. UPDATE posts SET ...), the column will not be updated automatically — use a database trigger if you need that guarantee.

TimestampMixin

Convenience mixin that combines CreatedAtMixin and UpdatedAtMixin. Equivalent to inheriting both.

from fastapi_toolsets.models import UUIDMixin, TimestampMixin

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

    title: Mapped[str]

Composing mixins

All mixins can be combined in any order. The only constraint is that exactly one primary key must be defined — either via UUIDMixin or directly on the model.

from fastapi_toolsets.models import UUIDMixin, TimestampMixin

class Event(Base, UUIDMixin, TimestampMixin):
    __tablename__ = "events"
    name: Mapped[str]

class Counter(Base, UpdatedAtMixin):
    __tablename__ = "counters"
    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    value: Mapped[int]

API Reference