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Diffstat (limited to 'libs/sqlalchemy/ext/asyncio/result.py')
| -rw-r--r-- | libs/sqlalchemy/ext/asyncio/result.py | 976 |
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diff --git a/libs/sqlalchemy/ext/asyncio/result.py b/libs/sqlalchemy/ext/asyncio/result.py new file mode 100644 index 000000000..3dcb1cfd0 --- /dev/null +++ b/libs/sqlalchemy/ext/asyncio/result.py @@ -0,0 +1,976 @@ +# ext/asyncio/result.py +# Copyright (C) 2020-2023 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php +from __future__ import annotations + +import operator +from typing import Any +from typing import AsyncIterator +from typing import Optional +from typing import overload +from typing import Sequence +from typing import Tuple +from typing import TYPE_CHECKING +from typing import TypeVar + +from . import exc as async_exc +from ... import util +from ...engine import Result +from ...engine.result import _NO_ROW +from ...engine.result import _R +from ...engine.result import _WithKeys +from ...engine.result import FilterResult +from ...engine.result import FrozenResult +from ...engine.result import ResultMetaData +from ...engine.row import Row +from ...engine.row import RowMapping +from ...sql.base import _generative +from ...util.concurrency import greenlet_spawn +from ...util.typing import Literal +from ...util.typing import Self + +if TYPE_CHECKING: + from ...engine import CursorResult + from ...engine.result import _KeyIndexType + from ...engine.result import _UniqueFilterType + +_T = TypeVar("_T", bound=Any) +_TP = TypeVar("_TP", bound=Tuple[Any, ...]) + + +class AsyncCommon(FilterResult[_R]): + __slots__ = () + + _real_result: Result[Any] + _metadata: ResultMetaData + + async def close(self) -> None: # type: ignore[override] + """Close this result.""" + + await greenlet_spawn(self._real_result.close) + + @property + def closed(self) -> bool: + """proxies the .closed attribute of the underlying result object, + if any, else raises ``AttributeError``. + + .. versionadded:: 2.0.0b3 + + """ + return self._real_result.closed # type: ignore + + +class AsyncResult(_WithKeys, AsyncCommon[Row[_TP]]): + """An asyncio wrapper around a :class:`_result.Result` object. + + The :class:`_asyncio.AsyncResult` only applies to statement executions that + use a server-side cursor. It is returned only from the + :meth:`_asyncio.AsyncConnection.stream` and + :meth:`_asyncio.AsyncSession.stream` methods. + + .. note:: As is the case with :class:`_engine.Result`, this object is + used for ORM results returned by :meth:`_asyncio.AsyncSession.execute`, + which can yield instances of ORM mapped objects either individually or + within tuple-like rows. Note that these result objects do not + deduplicate instances or rows automatically as is the case with the + legacy :class:`_orm.Query` object. For in-Python de-duplication of + instances or rows, use the :meth:`_asyncio.AsyncResult.unique` modifier + method. + + .. versionadded:: 1.4 + + """ + + __slots__ = () + + _real_result: Result[_TP] + + def __init__(self, real_result: Result[_TP]): + self._real_result = real_result + + self._metadata = real_result._metadata + self._unique_filter_state = real_result._unique_filter_state + self._post_creational_filter = None + + # BaseCursorResult pre-generates the "_row_getter". Use that + # if available rather than building a second one + if "_row_getter" in real_result.__dict__: + self._set_memoized_attribute( + "_row_getter", real_result.__dict__["_row_getter"] + ) + + @property + def t(self) -> AsyncTupleResult[_TP]: + """Apply a "typed tuple" typing filter to returned rows. + + The :attr:`_asyncio.AsyncResult.t` attribute is a synonym for + calling the :meth:`_asyncio.AsyncResult.tuples` method. + + .. versionadded:: 2.0 + + """ + return self # type: ignore + + def tuples(self) -> AsyncTupleResult[_TP]: + """Apply a "typed tuple" typing filter to returned rows. + + This method returns the same :class:`_asyncio.AsyncResult` object + at runtime, + however annotates as returning a :class:`_asyncio.AsyncTupleResult` + object that will indicate to :pep:`484` typing tools that plain typed + ``Tuple`` instances are returned rather than rows. This allows + tuple unpacking and ``__getitem__`` access of :class:`_engine.Row` + objects to by typed, for those cases where the statement invoked + itself included typing information. + + .. versionadded:: 2.0 + + :return: the :class:`_result.AsyncTupleResult` type at typing time. + + .. seealso:: + + :attr:`_asyncio.AsyncResult.t` - shorter synonym + + :attr:`_engine.Row.t` - :class:`_engine.Row` version + + """ + + return self # type: ignore + + @_generative + def unique(self, strategy: Optional[_UniqueFilterType] = None) -> Self: + """Apply unique filtering to the objects returned by this + :class:`_asyncio.AsyncResult`. + + Refer to :meth:`_engine.Result.unique` in the synchronous + SQLAlchemy API for a complete behavioral description. + + """ + self._unique_filter_state = (set(), strategy) + return self + + def columns(self, *col_expressions: _KeyIndexType) -> Self: + r"""Establish the columns that should be returned in each row. + + Refer to :meth:`_engine.Result.columns` in the synchronous + SQLAlchemy API for a complete behavioral description. + + """ + return self._column_slices(col_expressions) + + async def partitions( + self, size: Optional[int] = None + ) -> AsyncIterator[Sequence[Row[_TP]]]: + """Iterate through sub-lists of rows of the size given. + + An async iterator is returned:: + + async def scroll_results(connection): + result = await connection.stream(select(users_table)) + + async for partition in result.partitions(100): + print("list of rows: %s" % partition) + + Refer to :meth:`_engine.Result.partitions` in the synchronous + SQLAlchemy API for a complete behavioral description. + + """ + + getter = self._manyrow_getter + + while True: + partition = await greenlet_spawn(getter, self, size) + if partition: + yield partition + else: + break + + async def fetchall(self) -> Sequence[Row[_TP]]: + """A synonym for the :meth:`_asyncio.AsyncResult.all` method. + + .. versionadded:: 2.0 + + """ + + return await greenlet_spawn(self._allrows) + + async def fetchone(self) -> Optional[Row[_TP]]: + """Fetch one row. + + When all rows are exhausted, returns None. + + This method is provided for backwards compatibility with + SQLAlchemy 1.x.x. + + To fetch the first row of a result only, use the + :meth:`_asyncio.AsyncResult.first` method. To iterate through all + rows, iterate the :class:`_asyncio.AsyncResult` object directly. + + :return: a :class:`_engine.Row` object if no filters are applied, + or ``None`` if no rows remain. + + """ + row = await greenlet_spawn(self._onerow_getter, self) + if row is _NO_ROW: + return None + else: + return row + + async def fetchmany( + self, size: Optional[int] = None + ) -> Sequence[Row[_TP]]: + """Fetch many rows. + + When all rows are exhausted, returns an empty list. + + This method is provided for backwards compatibility with + SQLAlchemy 1.x.x. + + To fetch rows in groups, use the + :meth:`._asyncio.AsyncResult.partitions` method. + + :return: a list of :class:`_engine.Row` objects. + + .. seealso:: + + :meth:`_asyncio.AsyncResult.partitions` + + """ + + return await greenlet_spawn(self._manyrow_getter, self, size) + + async def all(self) -> Sequence[Row[_TP]]: + """Return all rows in a list. + + Closes the result set after invocation. Subsequent invocations + will return an empty list. + + :return: a list of :class:`_engine.Row` objects. + + """ + + return await greenlet_spawn(self._allrows) + + def __aiter__(self) -> AsyncResult[_TP]: + return self + + async def __anext__(self) -> Row[_TP]: + row = await greenlet_spawn(self._onerow_getter, self) + if row is _NO_ROW: + raise StopAsyncIteration() + else: + return row + + async def first(self) -> Optional[Row[_TP]]: + """Fetch the first row or ``None`` if no row is present. + + Closes the result set and discards remaining rows. + + .. note:: This method returns one **row**, e.g. tuple, by default. + To return exactly one single scalar value, that is, the first + column of the first row, use the + :meth:`_asyncio.AsyncResult.scalar` method, + or combine :meth:`_asyncio.AsyncResult.scalars` and + :meth:`_asyncio.AsyncResult.first`. + + Additionally, in contrast to the behavior of the legacy ORM + :meth:`_orm.Query.first` method, **no limit is applied** to the + SQL query which was invoked to produce this + :class:`_asyncio.AsyncResult`; + for a DBAPI driver that buffers results in memory before yielding + rows, all rows will be sent to the Python process and all but + the first row will be discarded. + + .. seealso:: + + :ref:`migration_20_unify_select` + + :return: a :class:`_engine.Row` object, or None + if no rows remain. + + .. seealso:: + + :meth:`_asyncio.AsyncResult.scalar` + + :meth:`_asyncio.AsyncResult.one` + + """ + return await greenlet_spawn(self._only_one_row, False, False, False) + + async def one_or_none(self) -> Optional[Row[_TP]]: + """Return at most one result or raise an exception. + + Returns ``None`` if the result has no rows. + Raises :class:`.MultipleResultsFound` + if multiple rows are returned. + + .. versionadded:: 1.4 + + :return: The first :class:`_engine.Row` or ``None`` if no row + is available. + + :raises: :class:`.MultipleResultsFound` + + .. seealso:: + + :meth:`_asyncio.AsyncResult.first` + + :meth:`_asyncio.AsyncResult.one` + + """ + return await greenlet_spawn(self._only_one_row, True, False, False) + + @overload + async def scalar_one(self: AsyncResult[Tuple[_T]]) -> _T: + ... + + @overload + async def scalar_one(self) -> Any: + ... + + async def scalar_one(self) -> Any: + """Return exactly one scalar result or raise an exception. + + This is equivalent to calling :meth:`_asyncio.AsyncResult.scalars` and + then :meth:`_asyncio.AsyncResult.one`. + + .. seealso:: + + :meth:`_asyncio.AsyncResult.one` + + :meth:`_asyncio.AsyncResult.scalars` + + """ + return await greenlet_spawn(self._only_one_row, True, True, True) + + @overload + async def scalar_one_or_none( + self: AsyncResult[Tuple[_T]], + ) -> Optional[_T]: + ... + + @overload + async def scalar_one_or_none(self) -> Optional[Any]: + ... + + async def scalar_one_or_none(self) -> Optional[Any]: + """Return exactly one scalar result or ``None``. + + This is equivalent to calling :meth:`_asyncio.AsyncResult.scalars` and + then :meth:`_asyncio.AsyncResult.one_or_none`. + + .. seealso:: + + :meth:`_asyncio.AsyncResult.one_or_none` + + :meth:`_asyncio.AsyncResult.scalars` + + """ + return await greenlet_spawn(self._only_one_row, True, False, True) + + async def one(self) -> Row[_TP]: + """Return exactly one row or raise an exception. + + Raises :class:`.NoResultFound` if the result returns no + rows, or :class:`.MultipleResultsFound` if multiple rows + would be returned. + + .. note:: This method returns one **row**, e.g. tuple, by default. + To return exactly one single scalar value, that is, the first + column of the first row, use the + :meth:`_asyncio.AsyncResult.scalar_one` method, or combine + :meth:`_asyncio.AsyncResult.scalars` and + :meth:`_asyncio.AsyncResult.one`. + + .. versionadded:: 1.4 + + :return: The first :class:`_engine.Row`. + + :raises: :class:`.MultipleResultsFound`, :class:`.NoResultFound` + + .. seealso:: + + :meth:`_asyncio.AsyncResult.first` + + :meth:`_asyncio.AsyncResult.one_or_none` + + :meth:`_asyncio.AsyncResult.scalar_one` + + """ + return await greenlet_spawn(self._only_one_row, True, True, False) + + @overload + async def scalar(self: AsyncResult[Tuple[_T]]) -> Optional[_T]: + ... + + @overload + async def scalar(self) -> Any: + ... + + async def scalar(self) -> Any: + """Fetch the first column of the first row, and close the result set. + + Returns ``None`` if there are no rows to fetch. + + No validation is performed to test if additional rows remain. + + After calling this method, the object is fully closed, + e.g. the :meth:`_engine.CursorResult.close` + method will have been called. + + :return: a Python scalar value, or ``None`` if no rows remain. + + """ + return await greenlet_spawn(self._only_one_row, False, False, True) + + async def freeze(self) -> FrozenResult[_TP]: + """Return a callable object that will produce copies of this + :class:`_asyncio.AsyncResult` when invoked. + + The callable object returned is an instance of + :class:`_engine.FrozenResult`. + + This is used for result set caching. The method must be called + on the result when it has been unconsumed, and calling the method + will consume the result fully. When the :class:`_engine.FrozenResult` + is retrieved from a cache, it can be called any number of times where + it will produce a new :class:`_engine.Result` object each time + against its stored set of rows. + + .. seealso:: + + :ref:`do_orm_execute_re_executing` - example usage within the + ORM to implement a result-set cache. + + """ + + return await greenlet_spawn(FrozenResult, self) + + @overload + def scalars( + self: AsyncResult[Tuple[_T]], index: Literal[0] + ) -> AsyncScalarResult[_T]: + ... + + @overload + def scalars(self: AsyncResult[Tuple[_T]]) -> AsyncScalarResult[_T]: + ... + + @overload + def scalars(self, index: _KeyIndexType = 0) -> AsyncScalarResult[Any]: + ... + + def scalars(self, index: _KeyIndexType = 0) -> AsyncScalarResult[Any]: + """Return an :class:`_asyncio.AsyncScalarResult` filtering object which + will return single elements rather than :class:`_row.Row` objects. + + Refer to :meth:`_result.Result.scalars` in the synchronous + SQLAlchemy API for a complete behavioral description. + + :param index: integer or row key indicating the column to be fetched + from each row, defaults to ``0`` indicating the first column. + + :return: a new :class:`_asyncio.AsyncScalarResult` filtering object + referring to this :class:`_asyncio.AsyncResult` object. + + """ + return AsyncScalarResult(self._real_result, index) + + def mappings(self) -> AsyncMappingResult: + """Apply a mappings filter to returned rows, returning an instance of + :class:`_asyncio.AsyncMappingResult`. + + When this filter is applied, fetching rows will return + :class:`_engine.RowMapping` objects instead of :class:`_engine.Row` + objects. + + :return: a new :class:`_asyncio.AsyncMappingResult` filtering object + referring to the underlying :class:`_result.Result` object. + + """ + + return AsyncMappingResult(self._real_result) + + +class AsyncScalarResult(AsyncCommon[_R]): + """A wrapper for a :class:`_asyncio.AsyncResult` that returns scalar values + rather than :class:`_row.Row` values. + + The :class:`_asyncio.AsyncScalarResult` object is acquired by calling the + :meth:`_asyncio.AsyncResult.scalars` method. + + Refer to the :class:`_result.ScalarResult` object in the synchronous + SQLAlchemy API for a complete behavioral description. + + .. versionadded:: 1.4 + + """ + + __slots__ = () + + _generate_rows = False + + def __init__(self, real_result: Result[Any], index: _KeyIndexType): + self._real_result = real_result + + if real_result._source_supports_scalars: + self._metadata = real_result._metadata + self._post_creational_filter = None + else: + self._metadata = real_result._metadata._reduce([index]) + self._post_creational_filter = operator.itemgetter(0) + + self._unique_filter_state = real_result._unique_filter_state + + def unique( + self, + strategy: Optional[_UniqueFilterType] = None, + ) -> Self: + """Apply unique filtering to the objects returned by this + :class:`_asyncio.AsyncScalarResult`. + + See :meth:`_asyncio.AsyncResult.unique` for usage details. + + """ + self._unique_filter_state = (set(), strategy) + return self + + async def partitions( + self, size: Optional[int] = None + ) -> AsyncIterator[Sequence[_R]]: + """Iterate through sub-lists of elements of the size given. + + Equivalent to :meth:`_asyncio.AsyncResult.partitions` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + + getter = self._manyrow_getter + + while True: + partition = await greenlet_spawn(getter, self, size) + if partition: + yield partition + else: + break + + async def fetchall(self) -> Sequence[_R]: + """A synonym for the :meth:`_asyncio.AsyncScalarResult.all` method.""" + + return await greenlet_spawn(self._allrows) + + async def fetchmany(self, size: Optional[int] = None) -> Sequence[_R]: + """Fetch many objects. + + Equivalent to :meth:`_asyncio.AsyncResult.fetchmany` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + return await greenlet_spawn(self._manyrow_getter, self, size) + + async def all(self) -> Sequence[_R]: + """Return all scalar values in a list. + + Equivalent to :meth:`_asyncio.AsyncResult.all` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + return await greenlet_spawn(self._allrows) + + def __aiter__(self) -> AsyncScalarResult[_R]: + return self + + async def __anext__(self) -> _R: + row = await greenlet_spawn(self._onerow_getter, self) + if row is _NO_ROW: + raise StopAsyncIteration() + else: + return row + + async def first(self) -> Optional[_R]: + """Fetch the first object or ``None`` if no object is present. + + Equivalent to :meth:`_asyncio.AsyncResult.first` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + return await greenlet_spawn(self._only_one_row, False, False, False) + + async def one_or_none(self) -> Optional[_R]: + """Return at most one object or raise an exception. + + Equivalent to :meth:`_asyncio.AsyncResult.one_or_none` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + return await greenlet_spawn(self._only_one_row, True, False, False) + + async def one(self) -> _R: + """Return exactly one object or raise an exception. + + Equivalent to :meth:`_asyncio.AsyncResult.one` except that + scalar values, rather than :class:`_engine.Row` objects, + are returned. + + """ + return await greenlet_spawn(self._only_one_row, True, True, False) + + +class AsyncMappingResult(_WithKeys, AsyncCommon[RowMapping]): + """A wrapper for a :class:`_asyncio.AsyncResult` that returns dictionary + values rather than :class:`_engine.Row` values. + + The :class:`_asyncio.AsyncMappingResult` object is acquired by calling the + :meth:`_asyncio.AsyncResult.mappings` method. + + Refer to the :class:`_result.MappingResult` object in the synchronous + SQLAlchemy API for a complete behavioral description. + + .. versionadded:: 1.4 + + """ + + __slots__ = () + + _generate_rows = True + + _post_creational_filter = operator.attrgetter("_mapping") + + def __init__(self, result: Result[Any]): + self._real_result = result + self._unique_filter_state = result._unique_filter_state + self._metadata = result._metadata + if result._source_supports_scalars: + self._metadata = self._metadata._reduce([0]) + + def unique( + self, + strategy: Optional[_UniqueFilterType] = None, + ) -> Self: + """Apply unique filtering to the objects returned by this + :class:`_asyncio.AsyncMappingResult`. + + See :meth:`_asyncio.AsyncResult.unique` for usage details. + + """ + self._unique_filter_state = (set(), strategy) + return self + + def columns(self, *col_expressions: _KeyIndexType) -> Self: + r"""Establish the columns that should be returned in each row.""" + return self._column_slices(col_expressions) + + async def partitions( + self, size: Optional[int] = None + ) -> AsyncIterator[Sequence[RowMapping]]: + """Iterate through sub-lists of elements of the size given. + + Equivalent to :meth:`_asyncio.AsyncResult.partitions` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + + getter = self._manyrow_getter + + while True: + partition = await greenlet_spawn(getter, self, size) + if partition: + yield partition + else: + break + + async def fetchall(self) -> Sequence[RowMapping]: + """A synonym for the :meth:`_asyncio.AsyncMappingResult.all` method.""" + + return await greenlet_spawn(self._allrows) + + async def fetchone(self) -> Optional[RowMapping]: + """Fetch one object. + + Equivalent to :meth:`_asyncio.AsyncResult.fetchone` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + + row = await greenlet_spawn(self._onerow_getter, self) + if row is _NO_ROW: + return None + else: + return row + + async def fetchmany( + self, size: Optional[int] = None + ) -> Sequence[RowMapping]: + """Fetch many rows. + + Equivalent to :meth:`_asyncio.AsyncResult.fetchmany` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + + return await greenlet_spawn(self._manyrow_getter, self, size) + + async def all(self) -> Sequence[RowMapping]: + """Return all rows in a list. + + Equivalent to :meth:`_asyncio.AsyncResult.all` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + + return await greenlet_spawn(self._allrows) + + def __aiter__(self) -> AsyncMappingResult: + return self + + async def __anext__(self) -> RowMapping: + row = await greenlet_spawn(self._onerow_getter, self) + if row is _NO_ROW: + raise StopAsyncIteration() + else: + return row + + async def first(self) -> Optional[RowMapping]: + """Fetch the first object or ``None`` if no object is present. + + Equivalent to :meth:`_asyncio.AsyncResult.first` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + return await greenlet_spawn(self._only_one_row, False, False, False) + + async def one_or_none(self) -> Optional[RowMapping]: + """Return at most one object or raise an exception. + + Equivalent to :meth:`_asyncio.AsyncResult.one_or_none` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + return await greenlet_spawn(self._only_one_row, True, False, False) + + async def one(self) -> RowMapping: + """Return exactly one object or raise an exception. + + Equivalent to :meth:`_asyncio.AsyncResult.one` except that + :class:`_engine.RowMapping` values, rather than :class:`_engine.Row` + objects, are returned. + + """ + return await greenlet_spawn(self._only_one_row, True, True, False) + + +class AsyncTupleResult(AsyncCommon[_R], util.TypingOnly): + """A :class:`_asyncio.AsyncResult` that's typed as returning plain + Python tuples instead of rows. + + Since :class:`_engine.Row` acts like a tuple in every way already, + this class is a typing only class, regular :class:`_asyncio.AsyncResult` is + still used at runtime. + + """ + + __slots__ = () + + if TYPE_CHECKING: + + async def partitions( + self, size: Optional[int] = None + ) -> AsyncIterator[Sequence[_R]]: + """Iterate through sub-lists of elements of the size given. + + Equivalent to :meth:`_result.Result.partitions` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + """ + ... + + async def fetchone(self) -> Optional[_R]: + """Fetch one tuple. + + Equivalent to :meth:`_result.Result.fetchone` except that + tuple values, rather than :class:`_engine.Row` + objects, are returned. + + """ + ... + + async def fetchall(self) -> Sequence[_R]: + """A synonym for the :meth:`_engine.ScalarResult.all` method.""" + ... + + async def fetchmany(self, size: Optional[int] = None) -> Sequence[_R]: + """Fetch many objects. + + Equivalent to :meth:`_result.Result.fetchmany` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + """ + ... + + async def all(self) -> Sequence[_R]: # noqa: A001 + """Return all scalar values in a list. + + Equivalent to :meth:`_result.Result.all` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + """ + ... + + async def __aiter__(self) -> AsyncIterator[_R]: + ... + + async def __anext__(self) -> _R: + ... + + async def first(self) -> Optional[_R]: + """Fetch the first object or ``None`` if no object is present. + + Equivalent to :meth:`_result.Result.first` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + + """ + ... + + async def one_or_none(self) -> Optional[_R]: + """Return at most one object or raise an exception. + + Equivalent to :meth:`_result.Result.one_or_none` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + """ + ... + + async def one(self) -> _R: + """Return exactly one object or raise an exception. + + Equivalent to :meth:`_result.Result.one` except that + tuple values, rather than :class:`_engine.Row` objects, + are returned. + + """ + ... + + @overload + async def scalar_one(self: AsyncTupleResult[Tuple[_T]]) -> _T: + ... + + @overload + async def scalar_one(self) -> Any: + ... + + async def scalar_one(self) -> Any: + """Return exactly one scalar result or raise an exception. + + This is equivalent to calling :meth:`_engine.Result.scalars` + and then :meth:`_engine.Result.one`. + + .. seealso:: + + :meth:`_engine.Result.one` + + :meth:`_engine.Result.scalars` + + """ + ... + + @overload + async def scalar_one_or_none( + self: AsyncTupleResult[Tuple[_T]], + ) -> Optional[_T]: + ... + + @overload + async def scalar_one_or_none(self) -> Optional[Any]: + ... + + async def scalar_one_or_none(self) -> Optional[Any]: + """Return exactly one or no scalar result. + + This is equivalent to calling :meth:`_engine.Result.scalars` + and then :meth:`_engine.Result.one_or_none`. + + .. seealso:: + + :meth:`_engine.Result.one_or_none` + + :meth:`_engine.Result.scalars` + + """ + ... + + @overload + async def scalar(self: AsyncTupleResult[Tuple[_T]]) -> Optional[_T]: + ... + + @overload + async def scalar(self) -> Any: + ... + + async def scalar(self) -> Any: + """Fetch the first column of the first row, and close the result + set. + + Returns ``None`` if there are no rows to fetch. + + No validation is performed to test if additional rows remain. + + After calling this method, the object is fully closed, + e.g. the :meth:`_engine.CursorResult.close` + method will have been called. + + :return: a Python scalar value , or ``None`` if no rows remain. + + """ + ... + + +_RT = TypeVar("_RT", bound="Result[Any]") + + +async def _ensure_sync_result(result: _RT, calling_method: Any) -> _RT: + cursor_result: CursorResult[Any] + + try: + is_cursor = result._is_cursor + except AttributeError: + # legacy execute(DefaultGenerator) case + return result + + if not is_cursor: + cursor_result = getattr(result, "raw", None) # type: ignore + else: + cursor_result = result # type: ignore + if cursor_result and cursor_result.context._is_server_side: + await greenlet_spawn(cursor_result.close) + raise async_exc.AsyncMethodRequired( + "Can't use the %s.%s() method with a " + "server-side cursor. " + "Use the %s.stream() method for an async " + "streaming result set." + % ( + calling_method.__self__.__class__.__name__, + calling_method.__name__, + calling_method.__self__.__class__.__name__, + ) + ) + return result |