storage.py 文件源码

def __call__(self, i, default=DEFAULT, cast=None, otherwise=None):
        """Allows to use a special syntax for fast-check of
        `request.args()` validity.
        :params:
            i: index
            default: use this value if arg not found
            cast: type cast
            otherwise:
                will be executed when:
                    - casts fail
                    - value not found, dont have default and otherwise is
                    especified
                can be:
                    - None: results in a 404
                    - str: redirect to this address
                    - callable: calls the function (nothing is passed)
        Example:
            You can use::
                request.args(0,default=0,cast=int,otherwise='http://error_url')
                request.args(0,default=0,cast=int,otherwise=lambda:...)
        """
        n = len(self)
        if 0 <= i < n or -n <= i < 0:
            value = self[i]
        elif default is DEFAULT:
            value = None
        else:
            value, cast, otherwise = default, False, False
        try:
            if cast:
                value = cast(value)
            if not value and otherwise:
                raise ValueError('Otherwise will raised.')
        except (ValueError, TypeError):
            from http import HTTP, redirect
            if otherwise is None:
                raise HTTP(404)
            elif isinstance(otherwise, str):
                redirect(otherwise)
            elif callable(otherwise):
                return otherwise()
            else:
                raise RuntimeError("invalid otherwise")
        return value