fast-repository 0.1.0

Interface-first repository pattern for FastAPI + SQLAlchemy. Declare the interface, get the implementation for free.

fast-repository

Interface-first repository pattern for FastAPI + SQLAlchemy.

Declare the repository interface, get the implementation for free.

Why

A repository keeps your domain layer depending on abstractions, but writing the same CRUD implementation for every entity is boilerplate. fast-repository removes that boilerplate while keeping the pattern intact:

from abc import ABC

from fast_repository import AbstractCRUDRepository, CRUDRepository

# Domain layer: depend on this interface.
class AbstractUserRepository(AbstractCRUDRepository[User], ABC): ...

# Infrastructure layer: zero boilerplate, all CRUD methods provided.
class UserRepository(CRUDRepository[User], AbstractUserRepository): ...

The entity class is captured from the generic argument (CRUDRepository[User]) at class-definition time — no constructor wiring, no metaclass tricks to learn.

Using a synchronous Session? SyncCRUDRepository and AbstractSyncCRUDRepository offer the same API without async/await.

Installation

pip install fast-repository

Requires Python 3.10+, SQLAlchemy 2.0+ (async or sync), and fastapi-pagination.

Usage

repo = UserRepository(session)  # AsyncSession

await repo.find(1)                                # SELECT ... WHERE id = 1
await repo.find(1, with_for_update=True)          # ... FOR UPDATE (row lock)
await repo.find(user_id=1, group_id=2)            # composite key by name
await repo.find_all(status="active")              # ... WHERE status = 'active'
await repo.find_all(id__in=[1, 2, 3])             # ... WHERE id IN (1, 2, 3)
await repo.find_all(age__ge=18, name__like="K%") # operator suffixes
await repo.find_all(or_(User.age < 18, User.age >= 65))  # raw SQLAlchemy expressions
await repo.find_all_paginated(params=Params(page=1, size=50), status="active")

await repo.save(user)
await repo.save_all(users)
await repo.delete(user)
await repo.delete_all(users)

Filter syntax

Keyword	SQL
column=value	column = value
column__in=[a, b]	column IN (a, b)
column__gt / __ge / __lt / __le	> / >= / < / <=
column__like / __ilike	LIKE / ILIKE
column__is=None	IS NULL

Unknown columns and operators raise InvalidFilterError instead of being silently ignored, so a typo can never return unfiltered data.

Customizing queries

Declare a base stmt to change relationship loading or apply a default filter to every read. Pass it as a class keyword argument:

class UserRepository(
    CRUDRepository[User],
    stmt=select(User).options(selectinload(User.posts)),
):
    ...

When omitted, reads default to select(User). For runtime customization you can also assign self.stmt on an instance.

Documentation

• Getting Started — install, define an entity, wire up a repository.
• Filtering — keyword filters, operator suffixes, primary-key lookups, pagination.
• Customizing queries — eager-load relationships or apply a default filter to every read.
• Transactions — control commit with the autocommit flag and group work into a unit of work.
• Soft delete — opt in to marking rows deleted instead of removing them.

Runnable examples cover basic CRUD, filtering, the autocommit flag, and a small FastAPI app.

License

MIT