216 lines
7.5 KiB
Python
216 lines
7.5 KiB
Python
from __future__ import annotations
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import dataclasses
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import decimal
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import json
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import typing as t
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import uuid
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import weakref
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from datetime import date
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from werkzeug.http import http_date
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if t.TYPE_CHECKING: # pragma: no cover
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from werkzeug.sansio.response import Response
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from ..sansio.app import App
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class JSONProvider:
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"""A standard set of JSON operations for an application. Subclasses
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of this can be used to customize JSON behavior or use different
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JSON libraries.
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To implement a provider for a specific library, subclass this base
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class and implement at least :meth:`dumps` and :meth:`loads`. All
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other methods have default implementations.
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To use a different provider, either subclass ``Flask`` and set
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:attr:`~flask.Flask.json_provider_class` to a provider class, or set
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:attr:`app.json <flask.Flask.json>` to an instance of the class.
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:param app: An application instance. This will be stored as a
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:class:`weakref.proxy` on the :attr:`_app` attribute.
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.. versionadded:: 2.2
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"""
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def __init__(self, app: App) -> None:
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self._app: App = weakref.proxy(app)
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def dumps(self, obj: t.Any, **kwargs: t.Any) -> str:
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"""Serialize data as JSON.
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:param obj: The data to serialize.
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:param kwargs: May be passed to the underlying JSON library.
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"""
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raise NotImplementedError
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def dump(self, obj: t.Any, fp: t.IO[str], **kwargs: t.Any) -> None:
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"""Serialize data as JSON and write to a file.
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:param obj: The data to serialize.
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:param fp: A file opened for writing text. Should use the UTF-8
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encoding to be valid JSON.
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:param kwargs: May be passed to the underlying JSON library.
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"""
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fp.write(self.dumps(obj, **kwargs))
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def loads(self, s: str | bytes, **kwargs: t.Any) -> t.Any:
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"""Deserialize data as JSON.
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:param s: Text or UTF-8 bytes.
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:param kwargs: May be passed to the underlying JSON library.
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"""
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raise NotImplementedError
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def load(self, fp: t.IO[t.AnyStr], **kwargs: t.Any) -> t.Any:
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"""Deserialize data as JSON read from a file.
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:param fp: A file opened for reading text or UTF-8 bytes.
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:param kwargs: May be passed to the underlying JSON library.
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"""
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return self.loads(fp.read(), **kwargs)
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def _prepare_response_obj(
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self, args: tuple[t.Any, ...], kwargs: dict[str, t.Any]
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) -> t.Any:
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if args and kwargs:
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raise TypeError("app.json.response() takes either args or kwargs, not both")
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if not args and not kwargs:
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return None
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if len(args) == 1:
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return args[0]
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return args or kwargs
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def response(self, *args: t.Any, **kwargs: t.Any) -> Response:
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"""Serialize the given arguments as JSON, and return a
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:class:`~flask.Response` object with the ``application/json``
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mimetype.
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The :func:`~flask.json.jsonify` function calls this method for
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the current application.
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Either positional or keyword arguments can be given, not both.
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If no arguments are given, ``None`` is serialized.
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:param args: A single value to serialize, or multiple values to
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treat as a list to serialize.
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:param kwargs: Treat as a dict to serialize.
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"""
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obj = self._prepare_response_obj(args, kwargs)
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return self._app.response_class(self.dumps(obj), mimetype="application/json")
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def _default(o: t.Any) -> t.Any:
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if isinstance(o, date):
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return http_date(o)
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if isinstance(o, (decimal.Decimal, uuid.UUID)):
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return str(o)
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if dataclasses and dataclasses.is_dataclass(o):
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return dataclasses.asdict(o) # type: ignore[arg-type]
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if hasattr(o, "__html__"):
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return str(o.__html__())
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raise TypeError(f"Object of type {type(o).__name__} is not JSON serializable")
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class DefaultJSONProvider(JSONProvider):
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"""Provide JSON operations using Python's built-in :mod:`json`
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library. Serializes the following additional data types:
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- :class:`datetime.datetime` and :class:`datetime.date` are
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serialized to :rfc:`822` strings. This is the same as the HTTP
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date format.
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- :class:`uuid.UUID` is serialized to a string.
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- :class:`dataclasses.dataclass` is passed to
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:func:`dataclasses.asdict`.
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- :class:`~markupsafe.Markup` (or any object with a ``__html__``
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method) will call the ``__html__`` method to get a string.
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"""
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default: t.Callable[[t.Any], t.Any] = staticmethod(_default) # type: ignore[assignment]
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"""Apply this function to any object that :meth:`json.dumps` does
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not know how to serialize. It should return a valid JSON type or
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raise a ``TypeError``.
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"""
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ensure_ascii = True
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"""Replace non-ASCII characters with escape sequences. This may be
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more compatible with some clients, but can be disabled for better
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performance and size.
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"""
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sort_keys = True
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"""Sort the keys in any serialized dicts. This may be useful for
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some caching situations, but can be disabled for better performance.
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When enabled, keys must all be strings, they are not converted
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before sorting.
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"""
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compact: bool | None = None
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"""If ``True``, or ``None`` out of debug mode, the :meth:`response`
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output will not add indentation, newlines, or spaces. If ``False``,
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or ``None`` in debug mode, it will use a non-compact representation.
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"""
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mimetype = "application/json"
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"""The mimetype set in :meth:`response`."""
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def dumps(self, obj: t.Any, **kwargs: t.Any) -> str:
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"""Serialize data as JSON to a string.
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Keyword arguments are passed to :func:`json.dumps`. Sets some
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parameter defaults from the :attr:`default`,
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:attr:`ensure_ascii`, and :attr:`sort_keys` attributes.
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:param obj: The data to serialize.
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:param kwargs: Passed to :func:`json.dumps`.
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"""
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kwargs.setdefault("default", self.default)
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kwargs.setdefault("ensure_ascii", self.ensure_ascii)
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kwargs.setdefault("sort_keys", self.sort_keys)
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return json.dumps(obj, **kwargs)
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def loads(self, s: str | bytes, **kwargs: t.Any) -> t.Any:
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"""Deserialize data as JSON from a string or bytes.
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:param s: Text or UTF-8 bytes.
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:param kwargs: Passed to :func:`json.loads`.
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"""
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return json.loads(s, **kwargs)
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def response(self, *args: t.Any, **kwargs: t.Any) -> Response:
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"""Serialize the given arguments as JSON, and return a
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:class:`~flask.Response` object with it. The response mimetype
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will be "application/json" and can be changed with
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:attr:`mimetype`.
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If :attr:`compact` is ``False`` or debug mode is enabled, the
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output will be formatted to be easier to read.
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Either positional or keyword arguments can be given, not both.
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If no arguments are given, ``None`` is serialized.
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:param args: A single value to serialize, or multiple values to
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treat as a list to serialize.
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:param kwargs: Treat as a dict to serialize.
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"""
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obj = self._prepare_response_obj(args, kwargs)
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dump_args: dict[str, t.Any] = {}
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if (self.compact is None and self._app.debug) or self.compact is False:
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dump_args.setdefault("indent", 2)
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else:
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dump_args.setdefault("separators", (",", ":"))
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return self._app.response_class(
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f"{self.dumps(obj, **dump_args)}\n", mimetype=self.mimetype
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)
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