snekql 0.2.0

Async typed query builder and runtime for SQLite and MariaDB

snekql

snekql is a Python async-first query builder and query runtime for SQL. It gives applications explicit SQL-shaped operations, typed model declarations, runtime validation, startup schema checks, and transaction- based execution without becoming an ORM.

Install

uv add snekql                 # Query Builder and backend namespaces only
uv add 'snekql[aiosqlite]'    # SQLite Query Runtime
uv add 'snekql[aiomysql]'     # MariaDB Query Runtime

snekql requires Python 3.14 or newer. Database drivers are optional backend extras. The base snekql install is enough for importing the Query Builder and backend namespaces, but runtime initialization requires the matching backend extra.

Quick start

from __future__ import annotations

from datetime import datetime
from pathlib import Path

from snekql import (
    MISSING,
    CurrentTimestamp,
    Database,
    DateTime,
    Fetched,
    Integer,
    Model,
    Pending,
    StructuredLogger,
    Text,
    insert,
    select,
)


class User[S = Pending](Model[S, "User[Fetched]"]):
    id: User.GenCol[int] = Integer(
        primary_key=True,
        auto_increment=True,
        default=MISSING,
    )
    email: User.Col[str] = Text(nullable=False, unique=True)
    status: User.Col[str] = Text(nullable=False, default="active")
    created_at: User.GenCol[datetime] = DateTime(
        server_default=CurrentTimestamp(),
        default=MISSING,
    )


async def main(logger: StructuredLogger) -> None:
    db = await Database.initialize(
        logger,
        database=Path("app.db"),
        models=[User],
        schema_policy="strict",
        pool_size=5,
        acquire_timeout=30.0,
    )
    try:
        async with db.transaction(timeout=5.0) as tx:
            await tx.execute(insert(User(email="[e-mail]")))
            user = await tx.fetch_one(
                select(User).where(User.email.eq("[e-mail]")),
            )
            if user is not None:
                print(user.email)
    finally:
        await db.close()

Model declaration

Models directly subclass Model[S, "ModelName[Fetched]"]. Application-created instances are Pending; database reads return Fetched instances.

class AuditLog[S = Pending](Model[S, "AuditLog[Fetched]"]):
    __tablename__ = "audit_log"

    id: AuditLog.GenCol[int] = Integer(
        primary_key=True,
        auto_increment=True,
        default=MISSING,
    )
    message: AuditLog.Col[str] = Text(nullable=False)
    created_at: AuditLog.GenCol[datetime] = DateTime(
        server_default=CurrentTimestamp(),
        default=MISSING,
    )

Rules to remember:

• Col[T] is a normal persisted column.
• GenCol[T] is server/generated; pending values may be MISSING, fetched values are T.
• If __tablename__ is omitted, class names become snake_case table names.
• Models are immutable after construction/materialization.
• Fetched models are produced by database reads only.

Storage classes

• Integer
• Real
• Text
• Blob
• Json stores JSON text.
• Boolean stores 0 / 1 in an INTEGER column.
• DateTime stores UTC text as YYYY-MM-DDTHH:MM:SS.SSSZ.

All storage declarations accept unique=True for column-level unique indexes. SQLite allows multiple NULL values in a unique index, so use nullable=False when uniqueness should also require a value. Primary-key columns reject unique=True because it is redundant.

CurrentTimestamp() is the only v1 server default and is valid only on DateTime GenCol fields.

Indexes

Use Index(...) in __indexes__ for table-level indexes:

from snekql import Index

class User[S = Pending](Model[S, "User[Fetched]"]):
    email: User.Col[str] = Text(nullable=False, unique=True)
    status: User.Col[str] = Text(nullable=False)
    tenant_id: User.Col[int] = Integer(nullable=False)

    __indexes__ = [
        Index(status),
        Index(tenant_id, email, unique=True),
        Index(tenant_id, name="ix_user_tenant_custom"),
    ]

Index declarations accept column descriptors only. Names are inferred as ix_<table>_<columns> or ux_<table>_<columns> unless name= is supplied.

Queries

Queries are immutable. Chaining returns new query objects.

from snekql import delete, insert, select, update

select(User).all()
select(User.email).where(User.status.eq("active"))
select(User.email, User.status).where(User.email.like("[e-mail]"))

insert(User(email="[e-mail]"))

update(User).set(User.status.to("disabled")).where(
    User.email.eq("[e-mail]"),
)

delete(User).where(User.email.eq("[e-mail]"))
delete(User).all()  # explicit full-table delete

Filtering is explicit: select, update, and delete must choose exactly one of .where(...) or .all() before execution. Predicates use methods such as .eq(...), .ne(...), .is_null(), .in_(...), .like(...); Python comparison operators are not part of the v1 API.

Runtime

Database.initialize(logger, ...) is the only public construction path. Select a backend with its namespace config. SQLite can be selected explicitly with the backend namespace, while the original SQLite keyword form remains supported.

from snekql import sqlite

db = await Database.initialize(logger, sqlite.Config(database=Path("app.db")), models=[User])
legacy_db = await Database.initialize(logger, database=Path("app.db"), models=[User])
memory_db = await Database.initialize(logger, sqlite.Config(database=":memory:"))

snekql requires a structured logger. The logger must use the structlog-style shape logger.debug("event", field=value). stdlib logging.Logger is not accepted directly; wrap it in an adapter if needed.

class AppLogger:
    def debug(self, event: str, **fields: object) -> None: ...
    def info(self, event: str, **fields: object) -> None: ...
    def warning(self, event: str, **fields: object) -> None: ...
    def error(self, event: str, **fields: object) -> None: ...


logger = AppLogger()
db = await Database.initialize(
    logger,
    sqlite.Config(database=Path("app.db")),
    models=[User],
)

A stdlib logger can be adapted at the application boundary:

class StdlibStructuredLogger:
    def __init__(self, logger: logging.Logger) -> None:
        self.logger = logger

    def debug(self, event: str, **fields: object) -> None:
        self.logger.debug(event, extra=fields)

    def info(self, event: str, **fields: object) -> None:
        self.logger.info(event, extra=fields)

    def warning(self, event: str, **fields: object) -> None:
        self.logger.warning(event, extra=fields)

    def error(self, event: str, **fields: object) -> None:
        self.logger.error(event, extra=fields)

MariaDB models should use the MariaDB namespace so backend-specific columns and runtime checks agree:

from snekql import MISSING, Database, Fetched, Pending, insert, mariadb, select


class Account[S = Pending](mariadb.Model[S, "Account[Fetched]"]):
    id: Account.GenCol[int] = mariadb.Integer(
        primary_key=True,
        auto_increment=True,
        default=MISSING,
    )
    email: Account.Col[str] = mariadb.Text(nullable=False, unique=True)


config = mariadb.Config(
    database="app",
    host="127.0.0.1",
    port=3306,
    user="snekql",
    password="secret",
)

db = await Database.initialize(logger, config, models=[Account])
try:
    async with db.transaction() as tx:
        await tx.execute(insert(Account(email="[e-mail]")))
        account = await tx.fetch_one(
            select(Account).where(Account.email.eq("[e-mail]")),
        )
finally:
    await db.close()

Use transactions for all work:

async with db.transaction() as tx:
    rows = await tx.fetch_all(select(User).all())
    first_email = await tx.fetch_one(select(User.email).all())
    await tx.execute(update(User).set(User.status.to("inactive")).all())

Runtime methods:

• fetch_all(select(...)) returns all result rows.
• fetch_one(select(...)) returns the first row or None.
• execute(insert/update/delete) returns None.
• close() is async and idempotent after a successful close.

Schema startup

When initialized with models=[...], snekql:

1. Preserves model order.
2. Rejects duplicate resolved table and index names.
3. Creates missing backend tables and their indexes.
4. Verifies existing tables and indexes with backend metadata: SQLite compares deterministic STRICT DDL; MariaDB compares normalized INFORMATION_SCHEMA metadata.
5. Treats drift according to schema_policy: "strict" raises, "warn" logs and continues.

Error model

Every intentional package-originated exception is a SnekqlError subclass. Use SnekqlError to catch all snekql failures, or catch narrower subclasses:

• ModelDeclarationError, ModelValidationError, FrozenModelError
• QueryConstructionError, QueryCompilationError
• DatabaseClosedError, PoolTimeoutError, TransactionClosedError, ExecutionError
• SchemaVerificationError

ExecutionError preserves sql and params for debugging. Structured query logs may also include SQL and params exactly as supplied to the database driver; snekql does not redact secrets.

Further reading

• Adoption and release confidence
• Why snekql is not an ORM
• Typing guide
• Schema startup and drift
• Error handling guide
• MariaDB integration PRD

Runnable examples live in examples/:

uv run python -m examples.basic_app
uv run pyright examples/typed_queries.py

Local validation uses uv run snektest. MariaDB integration tests start an unprivileged temporary mariadbd instance through tests/mariadb_server.py, so mariadbd and mariadb-install-db must be available on the test machine.

Public API

The package root is the public import surface. Prefer from snekql import ... over importing from internal modules.

Agent navigation map:

• snekql/model.py: model metaclass, table metadata, pending/fetched materialization.
• snekql/storage.py: column descriptors, SQLite storage metadata, value codecs.
• snekql/expressions.py: predicates, ordering, update assignments.
• snekql/query.py: query builders and SQL compilation.
• snekql/runtime.py: Database, Transaction, execution methods.
• snekql/_pool.py: internal async SQLite connection pool.
• snekql/schema.py: STRICT DDL generation and schema verification.
• snekql/errors.py: public exception hierarchy.
• tests/test_public_typing.py: type-checker prototypes for the public API.
• PRD.md: full v1 product contract.
• CONTEXT.md: project language and terminology.