strawberry-alchemy

Batteries-included toolkit for building Strawberry GraphQL APIs backed by SQLAlchemy

Source Code: https://github.com/Alteian/strawberry-alchemy

Documentation: docs/index.md · API reference

What is it?

strawberry-alchemy turns Strawberry GraphQL selection sets into a single optimized SQLAlchemy query — automatic selectinload for relationships, column deferral, and SQL EXISTS/COUNT annotations — and ships the supporting cast: filter inputs, Relay pagination, CRUD repositories, row-level security, permissions, and mapping helpers.

• No N+1 queries: nested selections become eager loads automatically
• Unrequested columns are deferred — you only fetch what the client asked for
• Declarative computed fields (hasComments, coverThumbUrl, counts) resolved by SQL subqueries
• AND/OR filters, relationship joins, and custom per-model filters from Strawberry inputs
• Relay Connection pagination with totalCount
• Async repositories with lifecycle hooks and cascade deletes
• Row-level access filters applied to every query — and to totalCount

Installation

pip install strawberry-alchemy
# or
uv add strawberry-alchemy

Requires Python >= 3.13, Strawberry GraphQL >= 0.220, SQLAlchemy, Pydantic v2.

Quick example

# models.py
import uuid

from sqlalchemy import ForeignKey
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column

from strawberry_alchemy.models import Base


class Post(Base):
    user_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("user.id"))
    title: Mapped[str]
    body: Mapped[str]

# access_filters.py
from typing import Any
from models import Post
from strawberry_alchemy.filtering import AccessControlFilter


class PostAccessFilter(AccessControlFilter):
    model_class = Post

    @staticmethod
    async def apply_filter(query: Any, model: type[Any], context_user: Any) -> Any:
        return query.where(model.user_id == context_user.id)

# types.py
import strawberry
from typing import ClassVar
from strawberry_alchemy import BaseNodeType


@strawberry.type
class PostType(BaseNodeType):
    access_filter: ClassVar = PostAccessFilter()

    title: str | None = strawberry.UNSET
    body: str | None = strawberry.UNSET

# queries.py
import strawberry
from strawberry.types import Info
from strawberry_alchemy import ListResult


@strawberry.type
class Query:
    @strawberry.field
    async def posts(self, info: Info, limit: int | None = None) -> ListResult[PostType]:
        return await PostType.resolve_list(info=info, limit=limit)

# schema.py
import strawberry
from strawberry.schema.config import StrawberryConfig

schema = strawberry.Schema(
    query=Query,
    config=StrawberryConfig(auto_camel_case=True, relay_max_results=100),
)

query {
  posts(limit: 10) {
    items { id title body }
    totalCount
  }
}

Your request context needs three things: get_session(), an identity/user attribute, and a db_execution_lock (see docs/getting-started.md#context-contract).

Documentation

Development

git clone https://github.com/Alteian/strawberry-alchemy.git
cd strawberry-alchemy
uv sync

# Lint & test
uv run ruff check .
uv run pytest -v

# Build
uv build

Contributing

See CONTRIBUTING.md for guidelines.

License

MIT