javascript - React 组件不会在更新状态时重新渲染

Question

我认为你知道更好的解决方案:我有一个包含我的猫的对象数组的文件:

var categories = [
  {
    "id": 1,
    "name" : "Faktury",
    "selected" : false
  },
  {
    "id": 2,
    "name" : "Telefony",
    "selected" : false
  },
  {
    "id": 3,
    "name" : "Komputery",
    "selected" : false
  },
  {
    "id": 4,
    "name" : "Rachunkowośc",
    "selected" : false
  },
  {
    "id": 5,
    "name" : "Finanse",
    "selected" : false
  }
];

我有:

<ul className="category">
  {this.state.categories.map((item,index) =>
    <li onClick={()=>this.filterCategory(item,index)} key={item.id} className={item.selected? 'active' : ''}>{item.name}</li>
  )}
</ul>

和我的过滤器类别:

filterCategory(item,index) {
  this.state.categories[index].selected = !this.state.categories[index].selected;
  this.forceUpdate();
}

你知道如何在没有 forceUpdate() 的情况下实现它吗？我已经读过堆栈我应该避免使用 this.forceUpdate()

Answer 1

使用 setState 会自动触发重新渲染，因此不要直接改变状态，而是使用 setState 来更新状态。

filterCategory(item,index){
   var categories = [...this.state.categories];
   categories[index].selected = !categories[index].selected;
   this.setState({categories})
}

根据文档:

NEVER mutate this.state directly, as calling setState() afterwards may replace the mutation you made. Treat this.state as if it were immutable.