ctx.py 文件源码

def copy_current_request_context(f):
    """A helper function that decorates a function to retain the current
    request context.  This is useful when working with greenlets.  The moment
    the function is decorated a copy of the request context is created and
    then pushed when the function is called.

    Example::

        import gevent
        from flask import copy_current_request_context

        @app.route('/')
        def index():
            @copy_current_request_context
            def do_some_work():
                # do some work here, it can access flask.request like you
                # would otherwise in the view function.
                ...
            gevent.spawn(do_some_work)
            return 'Regular response'

    .. versionadded:: 0.10
    """
    top = _request_ctx_stack.top
    if top is None:
        raise RuntimeError('This decorator can only be used at local scopes '
            'when a request context is on the stack.  For instance within '
            'view functions.')
    reqctx = top.copy()
    def wrapper(*args, **kwargs):
        with reqctx:
            return f(*args, **kwargs)
    return update_wrapper(wrapper, f)