React Native中的重置组件状态

Question

我只想重置某些（不是全部）状态。单击按钮时，应将present_count，total_count，present和total的值设置为其初始状态（0）。 subjects和text的状态应保持不变。

constructor(props) {
    super(props);
    this.state = { 
      subjects: [],
      text: "",
      present_count: [0, 0, 0, 0, 0, 0, 0],
      total_count: [0, 0, 0, 0, 0, 0, 0],
      present: 0,
      total: 0
    }
}

编辑：我正在使用AsyncStorage保存修改后的状态。

Answer 1

您可以创建一个对象来存储您要重置的状态的初始状态，如下所示：

const initState = {
   total: 0,
   present: 0,
   present_count: [0, 0, 0, 0, 0, 0, 0],
   total_count: [0, 0, 0, 0, 0, 0, 0],
}

然后您可以

this.setState({
   ...initialState
})

在您的按钮上的onClick

希望有帮助。 ^^

Answer 2

在这里使用扩展运算符可能会有用。

constructor(props) {
    super(props);
    this.defaultState = {
      present_count: [0, 0, 0, 0, 0, 0, 0],
      total_count: [0, 0, 0, 0, 0, 0, 0],
      present: 0,
      total: 0
    }
    this.state = { 
      subjects: [],
      text: "",
      ...defaultState,
    }
}
.
.
.
onClick = () => {
  this.setState({
    ...this.defaultState, // This will only pass in values from your defaultState and leave the others (subjects & text) alone
  });
}

Answer 3

您可以使用spread operator覆盖当前状态值，然后使用text，subjects的当前状态值：

// default state 
const defaultState = {
  subjects: [],
  text: "",
  present_count: [0, 0, 0, 0, 0, 0, 0],
  total_count: [0, 0, 0, 0, 0, 0, 0],
  present: 0,
  total: 0
}

// component constructor.
constructor(props) {
    super(props);
    this.state = defaultState;
}

// click event handler    
handleClick = () => {
  this.setState({
    ...defaultState,
    subjects: this.state.subjects,
    text: this.state.text
  });
}