""" Protocol objects representing different implementations of the same classes. """ # Copyright (C) 2020 The Psycopg Team from typing import Any, Callable, Generator, Mapping from typing import List, Optional, Sequence, Tuple, TypeVar, Union from typing import TYPE_CHECKING from typing_extensions import TypeAlias from . import pq from ._enums import PyFormat as PyFormat from ._compat import Protocol, LiteralString if TYPE_CHECKING: from . import sql from .rows import Row, RowMaker from .pq.abc import PGresult from .waiting import Wait, Ready from .connection import BaseConnection from ._adapters_map import AdaptersMap NoneType: type = type(None) # An object implementing the buffer protocol Buffer: TypeAlias = Union[bytes, bytearray, memoryview] Query: TypeAlias = Union[LiteralString, bytes, "sql.SQL", "sql.Composed"] Params: TypeAlias = Union[Sequence[Any], Mapping[str, Any]] ConnectionType = TypeVar("ConnectionType", bound="BaseConnection[Any]") PipelineCommand: TypeAlias = Callable[[], None] DumperKey: TypeAlias = Union[type, Tuple["DumperKey", ...]] # Waiting protocol types RV = TypeVar("RV") PQGenConn: TypeAlias = Generator[Tuple[int, "Wait"], "Ready", RV] """Generator for processes where the connection file number can change. This can happen in connection and reset, but not in normal querying. """ PQGen: TypeAlias = Generator["Wait", "Ready", RV] """Generator for processes where the connection file number won't change. """ class WaitFunc(Protocol): """ Wait on the connection which generated `PQgen` and return its final result. """ def __call__( self, gen: PQGen[RV], fileno: int, timeout: Optional[float] = None ) -> RV: ... # Adaptation types DumpFunc: TypeAlias = Callable[[Any], Buffer] LoadFunc: TypeAlias = Callable[[Buffer], Any] class AdaptContext(Protocol): """ A context describing how types are adapted. Example of `~AdaptContext` are `~psycopg.Connection`, `~psycopg.Cursor`, `~psycopg.adapt.Transformer`, `~psycopg.adapt.AdaptersMap`. Note that this is a `~typing.Protocol`, so objects implementing `!AdaptContext` don't need to explicitly inherit from this class. """ @property def adapters(self) -> "AdaptersMap": """The adapters configuration that this object uses.""" ... @property def connection(self) -> Optional["BaseConnection[Any]"]: """The connection used by this object, if available. :rtype: `~psycopg.Connection` or `~psycopg.AsyncConnection` or `!None` """ ... class Dumper(Protocol): """ Convert Python objects of type `!cls` to PostgreSQL representation. """ format: pq.Format """ The format that this class `dump()` method produces, `~psycopg.pq.Format.TEXT` or `~psycopg.pq.Format.BINARY`. This is a class attribute. """ oid: int """The oid to pass to the server, if known; 0 otherwise (class attribute).""" def __init__(self, cls: type, context: Optional[AdaptContext] = None): ... def dump(self, obj: Any) -> Buffer: """Convert the object `!obj` to PostgreSQL representation. :param obj: the object to convert. """ ... def quote(self, obj: Any) -> Buffer: """Convert the object `!obj` to escaped representation. :param obj: the object to convert. """ ... def get_key(self, obj: Any, format: PyFormat) -> DumperKey: """Return an alternative key to upgrade the dumper to represent `!obj`. :param obj: The object to convert :param format: The format to convert to Normally the type of the object is all it takes to define how to dump the object to the database. For instance, a Python `~datetime.date` can be simply converted into a PostgreSQL :sql:`date`. In a few cases, just the type is not enough. For example: - A Python `~datetime.datetime` could be represented as a :sql:`timestamptz` or a :sql:`timestamp`, according to whether it specifies a `!tzinfo` or not. - A Python int could be stored as several Postgres types: int2, int4, int8, numeric. If a type too small is used, it may result in an overflow. If a type too large is used, PostgreSQL may not want to cast it to a smaller type. - Python lists should be dumped according to the type they contain to convert them to e.g. array of strings, array of ints (and which size of int?...) In these cases, a dumper can implement `!get_key()` and return a new class, or sequence of classes, that can be used to identify the same dumper again. If the mechanism is not needed, the method should return the same `!cls` object passed in the constructor. If a dumper implements `get_key()` it should also implement `upgrade()`. """ ... def upgrade(self, obj: Any, format: PyFormat) -> "Dumper": """Return a new dumper to manage `!obj`. :param obj: The object to convert :param format: The format to convert to Once `Transformer.get_dumper()` has been notified by `get_key()` that this Dumper class cannot handle `!obj` itself, it will invoke `!upgrade()`, which should return a new `Dumper` instance, which will be reused for every objects for which `!get_key()` returns the same result. """ ... class Loader(Protocol): """ Convert PostgreSQL values with type OID `!oid` to Python objects. """ format: pq.Format """ The format that this class `load()` method can convert, `~psycopg.pq.Format.TEXT` or `~psycopg.pq.Format.BINARY`. This is a class attribute. """ def __init__(self, oid: int, context: Optional[AdaptContext] = None): ... def load(self, data: Buffer) -> Any: """ Convert the data returned by the database into a Python object. :param data: the data to convert. """ ... class Transformer(Protocol): types: Optional[Tuple[int, ...]] formats: Optional[List[pq.Format]] def __init__(self, context: Optional[AdaptContext] = None): ... @classmethod def from_context(cls, context: Optional[AdaptContext]) -> "Transformer": ... @property def connection(self) -> Optional["BaseConnection[Any]"]: ... @property def encoding(self) -> str: ... @property def adapters(self) -> "AdaptersMap": ... @property def pgresult(self) -> Optional["PGresult"]: ... def set_pgresult( self, result: Optional["PGresult"], *, set_loaders: bool = True, format: Optional[pq.Format] = None ) -> None: ... def set_dumper_types(self, types: Sequence[int], format: pq.Format) -> None: ... def set_loader_types(self, types: Sequence[int], format: pq.Format) -> None: ... def dump_sequence( self, params: Sequence[Any], formats: Sequence[PyFormat] ) -> Sequence[Optional[Buffer]]: ... def as_literal(self, obj: Any) -> bytes: ... def get_dumper(self, obj: Any, format: PyFormat) -> Dumper: ... def load_rows(self, row0: int, row1: int, make_row: "RowMaker[Row]") -> List["Row"]: ... def load_row(self, row: int, make_row: "RowMaker[Row]") -> Optional["Row"]: ... def load_sequence(self, record: Sequence[Optional[Buffer]]) -> Tuple[Any, ...]: ... def get_loader(self, oid: int, format: pq.Format) -> Loader: ...