dynamoxy

A typed, async DynamoDB ORM for Python, with a Rust core. Declare models with type hints (or pydantic), and get validated, atomic, observable DynamoDB access: repositories, queries with cursors, transactions with readable failures, unique constraints, optimistic locking, single-table design and an in-memory DynamoDB for tests.

import asyncio
from datetime import datetime

import dynamoxy
from dynamoxy import Attr, field, partition_key


class User(dynamoxy.Model, table="users"):
    user_id: Attr[str] = partition_key()
    email: Attr[str] = field(unique=True)
    name: Attr[str] = field(min_length=1)
    visits: Attr[int] = field(default=0)
    created_at: Attr[datetime] = dynamoxy.created_at()
    version: Attr[int] = dynamoxy.version()

    by_email = dynamoxy.GlobalIndex(partition_key=email)


async def main() -> None:
    async with dynamoxy.Client(region="eu-west-1") as client:  # or dynamoxy.testing.memory_client()
        await client.ensure_tables(User)
        users = client.repository(User)

        ada = await users.create(User(user_id="u1", email="ada@example.com", name="Ada"))
        await ada.increment(User.visits)  # atomic; `ada` is refreshed in place
        ada.name = "Ada Lovelace"
        await ada.save()  # only if nobody changed it meanwhile (version)

        try:
            await users.create(User(user_id="u2", email="ada@example.com", name="Imposter"))
        except dynamoxy.UniqueConstraintError as error:
            print(f"{error.field} is taken")

        found = await users.query(index=User.by_email, email="ada@example.com").first()
        print(found)


asyncio.run(main())

Already using pydantic?

Inherit from dynamoxy.PydanticModel instead of BaseModel and mark the key. Pydantic keeps validating, and the class stays a pydantic model, so the same Customer can be a FastAPI request or response model and a DynamoDB table (uv add 'dynamoxy[pydantic]'):

from typing import Annotated

from pydantic import BaseModel, Field

import dynamoxy


class Address(BaseModel):  # plain pydantic models nest as maps
    street: str
    city: str


class Customer(dynamoxy.PydanticModel, table="customers"):  # instead of BaseModel
    customer_id: Annotated[str, dynamoxy.PartitionKey()]
    email: Annotated[str, dynamoxy.Unique()]
    name: str = Field(min_length=1)
    address: Address | None = None


await client.ensure_tables(Customer)
customers = client.repository(Customer)
await customers.create(Customer(customer_id="c1", email="ada@example.com", name="Ada"))
customer = await customers.get("c1")  # a validated Customer

A model you would rather not touch can stay as it is: subclass it together with dynamoxy.PydanticModel and re-declare only the fields that need a marker, such as the key (see the pydantic guide).

Why dynamoxy

• Typed models: Attr[T] fields are values on instances and typed expression paths on the class (User.visits > 3); type checkers understand constructors and expressions. Pydantic models work too.
• Correct by default: validation before I/O, create that never overwrites, optimistic locking with version(), unique attributes enforced transactionally, automatic timestamps, conditions on every write, no values in expression strings.
• Every DynamoDB feature: queries and scans with cursors, global and local indexes, batches with unprocessed-item handling, transactions with per-operation cancellation reasons, TTL, streams, backups and point-in-time recovery, PartiQL, table management.
• Single-table design with key templates, derived index keys and mixed-entity collections.
• Observable: structured events and logging, hooks, middleware, OpenTelemetry spans and metrics, per-request cost accounting (dynamoxy.collect()).
• Testable: dynamoxy.testing.memory_client() is an in-memory DynamoDB with DynamoDB's semantics and fault injection; no Docker, no AWS account.
• Fast and robust: a Rust core (AWS SDK for Rust, Tokio) handles transport, retries with backoff, timeouts and batching; wheels for Linux (x86_64, aarch64, glibc and musl), macOS and Windows, CPython 3.12+.

Install

uv add dynamoxy               # or: pip install dynamoxy
uv add 'dynamoxy[pydantic]'   # pydantic models
uv add 'dynamoxy[otel]'       # OpenTelemetry

Documentation

AI agents: run dynamoxy guide (or read AGENT_GUIDE.md) before writing code with dynamoxy; application repositories can copy the skill in skills/dynamoxy. Agents changing dynamoxy itself start with AGENTS.md.

How it works

The Rust core (crates/dynamoxy-core) speaks DynamoDB through the AWS SDK for Rust, with its own retries, timeouts, batching, events and metrics, and contains a complete in-memory DynamoDB. A thin PyO3 binding exposes it to asyncio, and the Python package adds models, validation, repositories, transactions, constraints, hooks and OpenTelemetry.

Contributing

See CONTRIBUTING.md. The project is young (0.x): breaking changes are possible in minor versions and are called out in the changelog.

License

MIT