expression.py 文件源码

def _expression_func(self, op, *values, **kwargs):
        # for use by index ... bad
        values = map(self.typecast_for_storage, values)
        self.op = op
        self.express_args = values
        use_key = kwargs.get('use_key', False)
        if self.hash_key and op != 'eq':
            raise ValidationException('Query key condition not supported')
        elif self.hash_key or self.range_key or use_key:
            use_key = True
            func = getattr(Key(self.name), op, None)
        else:
            func = getattr(Attr(self.name), op, None)
        if not func:
            raise ValidationException('Query key condition not supported')
        return self, func(*values), use_key