from __future__ import annotations
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import logging
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import sys
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import typing as t
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from werkzeug.local import LocalProxy
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from .globals import request
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if t.TYPE_CHECKING: # pragma: no cover
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from .app import Flask
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@LocalProxy
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def wsgi_errors_stream() -> t.TextIO:
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"""Find the most appropriate error stream for the application. If a request
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is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``.
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If you configure your own :class:`logging.StreamHandler`, you may want to
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use this for the stream. If you are using file or dict configuration and
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can't import this directly, you can refer to it as
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``ext://flask.logging.wsgi_errors_stream``.
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"""
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return request.environ["wsgi.errors"] if request else sys.stderr
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def has_level_handler(logger: logging.Logger) -> bool:
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"""Check if there is a handler in the logging chain that will handle the
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given logger's :meth:`effective level <~logging.Logger.getEffectiveLevel>`.
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"""
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level = logger.getEffectiveLevel()
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current = logger
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while current:
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if any(handler.level <= level for handler in current.handlers):
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return True
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if not current.propagate:
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break
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current = current.parent # type: ignore
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return False
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#: Log messages to :func:`~flask.logging.wsgi_errors_stream` with the format
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#: ``[%(asctime)s] %(levelname)s in %(module)s: %(message)s``.
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default_handler = logging.StreamHandler(wsgi_errors_stream) # type: ignore
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default_handler.setFormatter(
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logging.Formatter("[%(asctime)s] %(levelname)s in %(module)s: %(message)s")
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)
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def create_logger(app: Flask) -> logging.Logger:
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"""Get the Flask app's logger and configure it if needed.
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The logger name will be the same as
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:attr:`app.import_name <flask.Flask.name>`.
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When :attr:`~flask.Flask.debug` is enabled, set the logger level to
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:data:`logging.DEBUG` if it is not set.
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If there is no handler for the logger's effective level, add a
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:class:`~logging.StreamHandler` for
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:func:`~flask.logging.wsgi_errors_stream` with a basic format.
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"""
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logger = logging.getLogger(app.name)
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if app.debug and not logger.level:
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logger.setLevel(logging.DEBUG)
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if not has_level_handler(logger):
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logger.addHandler(default_handler)
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return logger
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