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378
src/fastapi_toolsets/crud.py
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378
src/fastapi_toolsets/crud.py
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"""Generic async CRUD operations for SQLAlchemy models."""
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from collections.abc import Sequence
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from typing import Any, ClassVar, Generic, Self, TypeVar, cast
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from pydantic import BaseModel
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from sqlalchemy import and_, func, select
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from sqlalchemy import delete as sql_delete
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from sqlalchemy.dialects.postgresql import insert
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from sqlalchemy.exc import NoResultFound
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from sqlalchemy.ext.asyncio import AsyncSession
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from sqlalchemy.orm import DeclarativeBase
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from sqlalchemy.sql.roles import WhereHavingRole
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from .db import get_transaction
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from .exceptions import NotFoundError
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__all__ = [
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"AsyncCrud",
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"CrudFactory",
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]
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ModelType = TypeVar("ModelType", bound=DeclarativeBase)
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class AsyncCrud(Generic[ModelType]):
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"""Generic async CRUD operations for SQLAlchemy models.
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Subclass this and set the `model` class variable, or use `CrudFactory`.
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Example:
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class UserCrud(AsyncCrud[User]):
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model = User
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# Or use the factory:
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UserCrud = CrudFactory(User)
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# Then use it:
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user = await UserCrud.get(session, [User.id == 1])
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users = await UserCrud.get_multi(session, limit=10)
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"""
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model: ClassVar[type[DeclarativeBase]]
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@classmethod
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async def create(
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cls: type[Self],
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session: AsyncSession,
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obj: BaseModel,
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) -> ModelType:
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"""Create a new record in the database.
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Args:
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session: DB async session
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obj: Pydantic model with data to create
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Returns:
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Created model instance
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"""
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async with get_transaction(session):
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db_model = cls.model(**obj.model_dump())
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session.add(db_model)
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await session.refresh(db_model)
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return cast(ModelType, db_model)
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@classmethod
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async def get(
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cls: type[Self],
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session: AsyncSession,
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filters: list[Any],
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*,
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with_for_update: bool = False,
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load_options: list[Any] | None = None,
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) -> ModelType:
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"""Get exactly one record. Raises NotFoundError if not found.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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with_for_update: Lock the row for update
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load_options: SQLAlchemy loader options (e.g., selectinload)
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Returns:
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Model instance
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Raises:
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NotFoundError: If no record found
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MultipleResultsFound: If more than one record found
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"""
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q = select(cls.model).where(and_(*filters))
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if load_options:
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q = q.options(*load_options)
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if with_for_update:
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q = q.with_for_update()
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result = await session.execute(q)
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item = result.unique().scalar_one_or_none()
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if not item:
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raise NotFoundError()
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return cast(ModelType, item)
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@classmethod
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async def first(
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cls: type[Self],
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session: AsyncSession,
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filters: list[Any] | None = None,
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*,
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load_options: list[Any] | None = None,
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) -> ModelType | None:
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"""Get the first matching record, or None.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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load_options: SQLAlchemy loader options
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Returns:
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Model instance or None
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"""
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q = select(cls.model)
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if filters:
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q = q.where(and_(*filters))
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if load_options:
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q = q.options(*load_options)
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result = await session.execute(q)
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return cast(ModelType | None, result.unique().scalars().first())
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@classmethod
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async def get_multi(
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cls: type[Self],
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session: AsyncSession,
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*,
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filters: list[Any] | None = None,
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load_options: list[Any] | None = None,
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order_by: Any | None = None,
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limit: int | None = None,
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offset: int | None = None,
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) -> Sequence[ModelType]:
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"""Get multiple records from the database.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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load_options: SQLAlchemy loader options
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order_by: Column or list of columns to order by
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limit: Max number of rows to return
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offset: Rows to skip
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Returns:
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List of model instances
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"""
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q = select(cls.model)
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if filters:
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q = q.where(and_(*filters))
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if load_options:
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q = q.options(*load_options)
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if order_by is not None:
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q = q.order_by(order_by)
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if offset is not None:
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q = q.offset(offset)
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if limit is not None:
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q = q.limit(limit)
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result = await session.execute(q)
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return cast(Sequence[ModelType], result.unique().scalars().all())
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@classmethod
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async def update(
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cls: type[Self],
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session: AsyncSession,
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obj: BaseModel,
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filters: list[Any],
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*,
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exclude_unset: bool = True,
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exclude_none: bool = False,
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) -> ModelType:
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"""Update a record in the database.
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Args:
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session: DB async session
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obj: Pydantic model with update data
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filters: List of SQLAlchemy filter conditions
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exclude_unset: Exclude fields not explicitly set in the schema
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exclude_none: Exclude fields with None value
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Returns:
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Updated model instance
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Raises:
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NotFoundError: If no record found
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"""
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async with get_transaction(session):
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db_model = await cls.get(session=session, filters=filters)
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values = obj.model_dump(
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exclude_unset=exclude_unset, exclude_none=exclude_none
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)
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for key, value in values.items():
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setattr(db_model, key, value)
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await session.refresh(db_model)
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return db_model
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@classmethod
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async def upsert(
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cls: type[Self],
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session: AsyncSession,
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obj: BaseModel,
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index_elements: list[str],
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*,
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set_: BaseModel | None = None,
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where: WhereHavingRole | None = None,
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) -> ModelType | None:
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"""Create or update a record (PostgreSQL only).
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Uses INSERT ... ON CONFLICT for atomic upsert.
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Args:
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session: DB async session
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obj: Pydantic model with data
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index_elements: Columns for ON CONFLICT (unique constraint)
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set_: Pydantic model for ON CONFLICT DO UPDATE SET
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where: WHERE clause for ON CONFLICT DO UPDATE
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Returns:
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Model instance
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"""
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async with get_transaction(session):
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values = obj.model_dump(exclude_unset=True)
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q = insert(cls.model).values(**values)
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if set_:
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q = q.on_conflict_do_update(
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index_elements=index_elements,
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set_=set_.model_dump(exclude_unset=True),
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where=where,
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)
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else:
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q = q.on_conflict_do_nothing(index_elements=index_elements)
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q = q.returning(cls.model)
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result = await session.execute(q)
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try:
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db_model = result.unique().scalar_one()
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except NoResultFound:
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db_model = await cls.first(
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session=session,
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filters=[getattr(cls.model, k) == v for k, v in values.items()],
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)
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return cast(ModelType | None, db_model)
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@classmethod
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async def delete(
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cls: type[Self],
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session: AsyncSession,
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filters: list[Any],
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) -> bool:
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"""Delete records from the database.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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Returns:
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True if deletion was executed
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"""
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async with get_transaction(session):
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q = sql_delete(cls.model).where(and_(*filters))
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await session.execute(q)
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return True
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@classmethod
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async def count(
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cls: type[Self],
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session: AsyncSession,
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filters: list[Any] | None = None,
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) -> int:
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"""Count records matching the filters.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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Returns:
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Number of matching records
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"""
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q = select(func.count()).select_from(cls.model)
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if filters:
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q = q.where(and_(*filters))
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result = await session.execute(q)
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return result.scalar_one()
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@classmethod
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async def exists(
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cls: type[Self],
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session: AsyncSession,
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filters: list[Any],
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) -> bool:
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"""Check if a record exists.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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Returns:
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True if at least one record matches
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"""
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q = select(cls.model).where(and_(*filters)).exists().select()
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result = await session.execute(q)
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return bool(result.scalar())
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@classmethod
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async def paginate(
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cls: type[Self],
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session: AsyncSession,
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*,
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filters: list[Any] | None = None,
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load_options: list[Any] | None = None,
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order_by: Any | None = None,
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page: int = 1,
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items_per_page: int = 20,
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) -> dict[str, Any]:
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"""Get paginated results with metadata.
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Args:
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session: DB async session
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filters: List of SQLAlchemy filter conditions
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load_options: SQLAlchemy loader options
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order_by: Column or list of columns to order by
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page: Page number (1-indexed)
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items_per_page: Number of items per page
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Returns:
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Dict with 'data' and 'pagination' keys
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"""
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filters = filters or []
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offset = (page - 1) * items_per_page
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items = await cls.get_multi(
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session,
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filters=filters,
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load_options=load_options,
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order_by=order_by,
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limit=items_per_page,
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offset=offset,
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)
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total_count = await cls.count(session, filters=filters)
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return {
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"data": items,
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"pagination": {
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"total_count": total_count,
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"items_per_page": items_per_page,
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"page": page,
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"has_more": page * items_per_page < total_count,
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},
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}
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def CrudFactory(
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model: type[ModelType],
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) -> type[AsyncCrud[ModelType]]:
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"""Create a CRUD class for a specific model.
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Args:
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model: SQLAlchemy model class
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Returns:
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AsyncCrud subclass bound to the model
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Example:
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from fastapi_toolsets.crud import CrudFactory
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from myapp.models import User, Post
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UserCrud = CrudFactory(User)
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PostCrud = CrudFactory(Post)
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# Usage
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user = await UserCrud.get(session, [User.id == 1])
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posts = await PostCrud.get_multi(session, filters=[Post.user_id == user.id])
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"""
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cls = type(f"Async{model.__name__}Crud", (AsyncCrud,), {"model": model})
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return cast(type[AsyncCrud[ModelType]], cls)
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