React如何给state中对象赋值和修改

如果state中是一个对象，该如何修改

    constructor(props) {
        super(props);
        this.state = {
            count: {
                price: 0.00,
                num: 1,
                total: 0,
            }
        }
    }
changeInput =  () =>{
//es6的assion方法
   let data = Object.assign({}, this.state.count, { total: 2, price: 1, num:2});
    this.setState({
        count: data
    })
}