百度都是通过计算属性来hack，其实官方有解决方法，直接看代码：

        data() {
            return {
                query: {
                    page: 1,
                    per_page: 10,
                    status: null,
                    order_num: null,
                    order_type: null,
                },
            };
        },
        watch: {
            'query.order_type'(val, oldV) {
                console.log(val, oldV)
                this.getData();
            },
            'query.status'(val,oldV){
                this.getData();
            }

image.png

https://laracasts.com/discuss/channels/vue/watch-returning-same-oldval-and-val
https://vuejs.org/v2/api/#vm-watch