expressions.py 文件源码

def __init__(self, *cases, **extra):
        if not all(isinstance(case, When) for case in cases):
            raise TypeError("Positional arguments must all be When objects.")
        default = extra.pop('default', None)
        output_field = extra.pop('output_field', None)
        super(Case, self).__init__(output_field)
        self.cases = list(cases)
        self.default = self._parse_expressions(default)[0]