1 added, 1 removed. Audit A to A.
---
name: advanced-alchemy
description: "Auto-activate for advanced_alchemy imports, alembic/, SQLAlchemyAsyncRepositoryService, SQLAlchemyAsyncConfig, repository_type, service_class, filters, or storage. Not for raw SQLAlchemy."
---
# Advanced Alchemy
## Match-Your-Framework — read first
advanced-alchemy ships first-party extensions for five web frameworks. If your project uses one of these, **jump directly to the matching integration guide and skip the others**:
- **Litestar** — `SQLAlchemyPlugin` with full DI, session store, CLI. The rest of this SKILL.md covers Litestar by default; also see [`references/litestar_plugin.md`](references/litestar_plugin.md).
- **FastAPI** → [`references/fastapi-integration.md`](references/fastapi-integration.md) — `AdvancedAlchemy(config=..., app=app)`, `Depends(alchemy.provide_session())` DI, `provide_service()`/`provide_filters()`, Alembic CLI via `assign_cli_group`.
- **Flask** → [`references/flask-integration.md`](references/flask-integration.md) — `AdvancedAlchemy(config=..., app=app)` or `init_app()` factory, pull-based `alchemy.get_sync_session()`, async-via-portal.
- **Sanic** → [`references/sanic-integration.md`](references/sanic-integration.md) — `AdvancedAlchemy(sqlalchemy_config=..., sanic_app=app)` (note: `sqlalchemy_config=` kwarg, not `config=`), sanic-ext DI, `request.ctx` sessions.
- **Starlette** → [`references/starlette-integration.md`](references/starlette-integration.md) — `AdvancedAlchemy(config=..., app=app)`, `request.state` session access, lifespan wrapping.
Shared topics that apply to every framework live in [`references/commit-modes.md`](references/commit-modes.md) (`commit_mode="manual"` / `"autocommit"` / `"autocommit_include_redirect"`) and [`references/multi-database.md`](references/multi-database.md) (bind-key pattern). Read the framework guide first, then those for depth.
The rest of this SKILL.md covers framework-agnostic topics: base classes, repositories, services, filters, custom types, caching, replicas, operations, and Alembic migrations.
## Overview
- Advanced Alchemy is NOT a raw ORM — it is a **service/repository layer** built on top of SQLAlchemy 2.0+ with opinionated base classes, audit mixins, and deep framework integrations (Litestar, FastAPI, Flask, Sanic). It provides:
+ Advanced Alchemy is NOT a raw ORM — it is a **service/repository layer** built on top of SQLAlchemy 2.0+ with opinionated base classes, audit mixins, and deep framework integrations (Litestar, FastAPI, Flask, Starlette, Sanic). It provides:
- **Base models** with automatic `id`, `created_at`, `updated_at` fields
- **Repository pattern** for type-safe async CRUD
- **Service layer** with lifecycle hooks (`to_model_on_create`, `to_model_on_update`)
- **Framework plugins** for automatic session/transaction management
- **Custom types**: `EncryptedString`, `FileObject`, `DateTimeUTC`, `GUID`
- **Alembic integration** for migrations via CLI
## Quick Reference
### Base Classes
| Base Class | PK Type | Audit Columns | When to Use |
| --- | --- | --- | --- |
| `UUIDAuditBase` | UUID v4 | `created_at`, `updated_at` | Default choice for most models |
| `UUIDBase` | UUID v4 | None | Lookup tables, tags, no audit needed |
| `UUIDv7AuditBase` | UUID v7 | `created_at`, `updated_at` | Time-sortable IDs (preferred over v6) |
| `BigIntAuditBase` | BigInt auto-increment | `created_at`, `updated_at` | Legacy systems, integer PKs |
| `NanoidAuditBase` | Nanoid string | `created_at`, `updated_at` | URL-friendly short IDs |
| `DeclarativeBase` | None (define yourself) | None | Full schema control |
### Repository Pattern
| Repository | Purpose |
| --- | --- |
| `SQLAlchemyAsyncRepository[Model]` | Standard async CRUD |
| `SQLAlchemyAsyncSlugRepository[Model]` | CRUD + automatic slug generation |
| `SQLAlchemyAsyncQueryRepository` | Complex read-only queries (no model_type) |
### Service Layer
| Service | Purpose |
| --- | --- |
| `SQLAlchemyAsyncRepositoryService[Model]` | Full CRUD with lifecycle hooks |
| `SQLAlchemyAsyncRepositoryReadService[Model]` | Read-only (get_many, get, count, exists) |
Key lifecycle hooks: `to_model_on_create`, `to_model_on_update`, `to_model_on_upsert`.
## Custom Types
| Type | Purpose | Notes |
| --- | --- | --- |
| `FileObject` | Object storage with lifecycle hooks | Tracks file state across session; auto-deletes on row delete via `StoredObject` tracker |
| `PasswordHash` | Hashed password storage | Supports Argon2, Passlib, and Pwdlib backends; hashes on assignment |
| `EncryptedString` | Transparent AES encryption at rest | Requires `ENCRYPTION_KEY` in config |
| `UUID6` / `UUID7` | Time-sortable UUID variants | UUID7 preferred — monotonic ordering with millisecond timestamp prefix |
| `DateTimeUTC` | Timezone-aware UTC datetime | Stores as UTC; raises on naive datetimes |
## Repository Service Layer
`SQLAlchemyAsyncRepositoryService` is the primary service base class. Key behaviors:
- **Dict-to-model conversion**: pass raw `dict` to `create()`, `update()`, `upsert()` — the service converts via `to_model_on_create` / `to_model_on_update` lifecycle hooks before persistence
- **Bulk operations**: `create_many(data)`, `update_many(data)`, `upsert_many(data)`, `delete_many(item_ids)` — batched in a single transaction; prefer over calling single-row methods in a loop
- **Lifecycle hooks**: `to_model_on_create`, `to_model_on_update`, `to_model_on_upsert` — override to transform input data, hash passwords, normalize strings, etc.
## Mixins
| Mixin | Fields Added | When to Use |
| --- | --- | --- |
| `AuditMixin` | `created_at`, `updated_at`, `created_by`, `updated_by` | Any model needing a full audit trail (who + when) |
| `SlugMixin` | `slug` (auto-generated) | URL-friendly identifiers derived from another field |
| `UniqueMixin` | `get_or_create` class method | Idempotent inserts for lookup/reference tables |
| `SentinelMixin` | `_sentinel` version column | Optimistic locking; raises `ConflictError` on stale writes |
## Litestar Integration
Use `SQLAlchemyPlugin` (composite of `SQLAlchemyInitPlugin` + `SQLAlchemySerializationPlugin`) for full integration:
- **`SQLAlchemyPlugin`**: registers session provider, transaction middleware, and ORM type encoders in one call
- **`SQLAlchemyDTO`**: generates Litestar DTOs directly from ORM models with `include`/`exclude` field control
- **Type encoders**: automatic serialization of `datetime`, `UUID`, `Decimal`, `Enum`, and custom column types
- **Exception handling**: `RepositoryError`, `ConflictError`, and `NotFoundError` map to HTTP 409/404 via built-in exception handlers — register with `app.exception_handlers`
## Code Style
- `__slots__` on non-model classes, `Mapped[]` typing for all columns
- `T | None` for optional fields (PEP 604 unions, never `Optional[T]`)
- Full type annotations on all function signatures
- Inner `Repo` class pattern inside service definitions
- Prefer `advanced_alchemy.*` imports; avoid deprecated `litestar.plugins.sqlalchemy` paths
- **`from __future__ import annotations` rule** — Advanced Alchemy model modules **avoid** `from __future__ import annotations` because SQLAlchemy 2.0 `Mapped[...]` columns are introspected at class-creation time. Consumer application modules (handlers, services, tests) MAY and typically SHOULD use it — canonical Litestar apps use it in 100+ files.
<workflow>
## Workflow
### Step 1: Define the Model
Choose the appropriate base class from the quick reference table. Use `UUIDAuditBase` unless you have a specific reason not to. Define columns with `Mapped[]` typing.
### Step 2: Create the Repository
Create a repository class with `model_type` set to your model. Use `SQLAlchemyAsyncRepository` for standard CRUD, `SQLAlchemyAsyncSlugRepository` if the model uses `SlugKey`.
### Step 3: Build the Service
Create a service class with an inner `Repo` class. Set `match_fields` for upsert logic. Add lifecycle hooks (`to_model_on_create`, `to_model_on_update`) for business logic transformations.
### Step 4: Wire into Framework
Use the framework plugin (Litestar, FastAPI, Flask, Sanic) to inject sessions and register the service as a dependency.
### Step 5: Generate Migration
Run `alembic revision --autogenerate -m "description"` to create the migration, then review and apply with `alembic upgrade head`.
</workflow>
<guardrails>
## Guardrails
- **Always use the service layer for business logic** — never put validation, hashing, or transformation logic directly in route handlers or repositories
- **Repositories are for data access only** — no business rules, no side effects beyond database operations
- **Never bypass the service layer** to call repository methods directly from handlers
- **Always set `match_fields`** on services that use `upsert()` to avoid duplicate-key errors
- **Use `schema_dump()` to convert DTOs** (Pydantic/msgspec/attrs) before passing to service methods
- **Prefer `UUIDAuditBase`** as default base class — only deviate when you have a concrete reason
- **Use `advanced_alchemy.*` imports** — the old `litestar.plugins.sqlalchemy` paths are deprecated
- **Model modules avoid `from __future__ import annotations`** — SQLAlchemy 2.0 needs the real `Mapped[...]` type at class-creation time. Consumer modules (handlers, services, tests) MAY use it.
</guardrails>
<validation>
### Validation Checkpoint
Before delivering code, verify:
- [ ] Model inherits from an Advanced Alchemy base class (not raw `DeclarativeBase` from SQLAlchemy)
- [ ] All columns use `Mapped[]` type annotations
- [ ] Service has an inner `Repo` class with `model_type` set
- [ ] Business logic lives in service lifecycle hooks, not in route handlers
- [ ] Imports come from `advanced_alchemy.*`, not deprecated paths
- [ ] Model module does NOT use `from __future__ import annotations` (consumer modules may)
</validation>
<example>
## Example
A complete `Tag` entity with model, repository, and service:
```python
"""Tag domain — model, repository, and service."""
from advanced_alchemy.base import UUIDAuditBase
from advanced_alchemy.repository import SQLAlchemyAsyncRepository
from advanced_alchemy.service import SQLAlchemyAsyncRepositoryService
from sqlalchemy.orm import Mapped, mapped_column
class Tag(UUIDAuditBase):
"""Tag model with audit trail."""
__tablename__ = "tag"
name: Mapped[str] = mapped_column(unique=True)
description: Mapped[str | None] = mapped_column(default=None)
class TagRepository(SQLAlchemyAsyncRepository[Tag]):
"""Data access for tags."""
model_type = Tag
class TagService(SQLAlchemyAsyncRepositoryService[Tag]):
"""Business logic for tags."""
class Repo(SQLAlchemyAsyncRepository[Tag]):
model_type = Tag
repository_type = Repo
match_fields = ["name"]
async def to_model_on_create(self, data):
"""Normalize tag name before creation."""
if isinstance(data, dict) and "name" in data:
data["name"] = data["name"].strip().lower()
return data
```
</example>
---
## References Index
> **Choosing between `advanced-alchemy` and `sqlspec`:** `advanced-alchemy` (this skill) gives you an opinionated ORM service layer with `UUIDAuditBase`, lifecycle hooks, repository / service / Alembic integration, and `OffsetPagination[T]` out of the box — pick it when you want a complete CRUD surface with attribute-style row access and you're happy inside the SQLAlchemy ecosystem. `sqlspec` gives you direct SQL control, 15+ driver adapters (asyncpg, oracledb, DuckDB, BigQuery, SQLite, and more), Arrow-native result streams for analytics, and a builder API when you need it — pick it when you want explicit SQL, heterogeneous database backends, or Arrow integration. Both skills integrate with Litestar via first-party plugins; see [`../sqlspec/SKILL.md`](../sqlspec/SKILL.md) for the raw-SQL / multi-adapter path.
For detailed guides and code examples, refer to the following documents in `references/`:
- **[Models](references/models.md)**
Base classes, mixins, special types, relationships, PII tracking, and deferred loading.
- **[Repositories](references/repositories.md)**
Async repository variants, configuration, slug repos, and query repos.
- **[Services](references/services.md)**
Service layer, lifecycle hooks, composite services, filtering, and pagination.
- **[Litestar Plugin](references/litestar_plugin.md)**
SQLAlchemy plugin config, DTOs, dependency injection, and session management.
- **[Migrations](references/migrations.md)**
Alembic integration, CLI commands, metadata registry, and multi-database support.
- **[Types](references/types.md)**
Complete catalog of custom column types: EncryptedString, FileObject, DateTimeUTC, GUID, PasswordHash, ColorType, and more.
- **[Base Classes](references/bases.md)**
Declarative base classes, UUID/BigInt/Nanoid variants, audit mixins, SlugKey, UniqueMixin, metadata registry, and custom base creation.
- **[Filters](references/filters.md)**
Filter system, pagination, SearchFilter, CollectionFilter, BeforeAfter, OrderBy, LimitOffset, and frontend integration patterns.
- **[Framework Integrations](references/frameworks.md)**
FastAPI, Flask, Starlette, and Sanic plugin setup, session management, and feature comparison across frameworks.
- **[Caching](references/caching.md)**
Dogpile.cache integration, CacheConfig, CacheManager API, automatic cache invalidation via session events, version-based list cache keys, singleflight stampede protection, and serialization.
- **[Read Replicas](references/replicas.md)**
Read/write routing, RoutingConfig, engine groups, RoundRobinSelector/RandomSelector, sticky-after-write consistency, context managers for explicit routing, and RoutingAsyncSessionMaker.
- **[Storage (obstore)](references/storage.md)**
FileObject and StoredObject types, ObstoreBackend and FSSpecBackend configuration (S3, GCS, Azure, local), StorageRegistry, presigned URL generation, automatic file lifecycle via session tracker, and Pydantic integration.
- **[Operations, Listeners, Serialization](references/operations.md)**
`OnConflictUpsert` / `MergeStatement` dialect-aware upsert building blocks, session event listeners (FileObject, cache invalidation, `touch_updated_timestamp`), and the msgspec-first `encode_json` / `decode_json` used across the library.
---
## Official References
- <https://advanced-alchemy.litestar.dev/latest/>
- <https://advanced-alchemy.litestar.dev/latest/usage/services.html>
- <https://advanced-alchemy.litestar.dev/latest/usage/cli.html>
- <https://advanced-alchemy.litestar.dev/latest/usage/modeling/types.html>
- <https://advanced-alchemy.litestar.dev/latest/reference/types.html>
- <https://advanced-alchemy.litestar.dev/latest/changelog.html>
- <https://docs.litestar.dev/2/release-notes/changelog.html>
- <https://docs.sqlalchemy.org/en/20/orm/quickstart.html>
## Shared Styleguide Baseline
- Use shared styleguides for generic language/framework rules to reduce duplication in this skill.
- [General Principles](../litestar-styleguide/references/general.md)
- [Python](../litestar-styleguide/references/python.md)
- [Litestar](../litestar-styleguide/references/litestar.md)
- Keep this skill focused on tool-specific workflows, edge cases, and integration details.