React - 类内的 useContext [英] React - useContext inside class

问题描述

我是 React 新手，我想在我的班级中使用 useContext，我该如何解决这个问题?这是我当前代码的示例

I'm newbie in react and i want use useContext inside my class, how do i solve this? This is example of my current code right now

import { Context } from '../context/ChatListContext'

const ChatList = ({ onAction }) => {
    const {state, fetchChatList} = useContext(Context)

我对我的班级也有同样的期待

And i'm expecting the same for my class

import { Context } from '../context/ChatListContext'

class MainScreen extends Component {

//const {state, fetchChatList} = useContext(Context) *how do i declare this?

  constructor(props) {
    super(props)
    this.state = { loading: true, showAction: false }
    setTimeout(() => {
      StatusBar.setBackgroundColor(primary)
    }, 100)
  }
...
}

有人能指教我吗?

推荐答案

useContext 是一个无法在类组件中使用的钩子.对于类组件，您定义一个 static contextType

useContext is a hook that can't be used in a class component. For a class component you define a static contextType

import { Context } from '../context/ChatListContext'

class MainScreen extends Component {

 static contextType = Context

  constructor(props) {
    super(props)
    this.state = { loading: true, showAction: false }
    setTimeout(() => {
      StatusBar.setBackgroundColor(primary)
    }, 100)
  }
...
  render() {
       const {state, fetchChatList} =this.context;
  }
}

这篇关于React - 类内的 useContext的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！