How to update state from other component?

问题

I am using react native and react navigation for routing.

How to update state from another component/page?

HomeScreen

export class HomeScreen extends Component {
  constructor(){
    this.state = {
      test: ''
    }
  }

  updateState = ()=>{
    this.setState({test:'new value'});
  }

 }



SideMenuScreen
import { HomeScreen } from "./home"; 

export class SideMenuScreen extends Component {

  updateHomeState = ()=>{
    let oHome = new HomeScreen(); 
    oHome.updateState();
  }

}

My App.js and routing and sidemenu config as below :

import { createAppContainer, createDrawerNavigator } from "react-navigation";
import { SideMenuScreen } from "./screens/Sidemenu";
import { HomeScreen } from "./screens/Home";

export default class App extends Component {
  render() {
    return(
      <AppContainer></AppContainer>
    );
  }
}

const AppNavigator = createDrawerNavigator(
  {Home: HomeScreen, 
    other: otherpage},
  {
    contentComponent: SideMenuScreen
  }
);

const AppContainer = createAppContainer(AppNavigator);

updateState executing but not updating state.

回答1:

Since you're not haveing Parent-Child relationship between your components ... thi s could be accomplished through Redux Action

HomeScreen;

export class HomeScreen extends Component {
  constructor() {
    this.state = {
      test: ""
    };
  }

  componentWillReceiveProps(nextProps) {
    const { test: nextTest } = nextProps;
    const { test } = this.props;

    if (nextTest !== test) {
        this.setState({ test: nextTest });
    }
  }

}

const mapStateToProps = ({ yourReducerName: test }) => ({ test });
export connect(mapStateToProps)(HomeScreen);

import { HomeScreen } from "./home";
import { connect } from "tls";

class SideMenuScreen extends Component {
  updateHomeState = () => {
    const { updateHomeStateAction } = this.props;

    updateHomeStateAction({ test: 'New Value' });
  };
}

export default connect(null, { updateHomeStateAction })(SideMenuScreen);

回答2:

If you have to update from the child component

You will have to pass down the Handlers from the component which holds the state to update the values, child component can make use of these handlers to update the state

If you have to update from some other location

You will have to do a level up the State and follow the same has above.

LevelUpComponent

export class App extends Component {
  constructor(){
    this.state = {
      test: ''
    }
  }

  updateState = (values)=>{
    this.setState(values);
  }

  render(){
    return <div>
     <HomeScreen></HomeScreen>
     <SideMenuScreen updateState={this.updateState}></SideMenuScreen>
     </div>
  }
 }

回答3:

You can do this by using ref.

HomeScreen 

export class HomeScreen extends Component {
  constructor(){
    this.state = {
      test: ''
    }
  }

  updateState = ()=>{
    this.setState({test:'new value'});
  }

 }



SideMenuScreen
import { HomeScreen } from "./home"; 

export class SideMenuScreen extends Component {

  updateHomeState = ()=>{
    this.homeScreen.updateState();
  }

render(){
return(
<HomeScreen ref={(ele) => this.homeScreen = ele}/>
);
}

}

回答4:

when you navigate to next screen pass this function in params,

this.props.navigate("SideMenuScreen",{update:this.updateState});

And in your side menu screen, call it using props,

this.props.navigation.state.params.update();//you can pass params also if needed

来源：https://stackoverflow.com/questions/55572323/how-to-update-state-from-other-component

标签

reactjs

react-native

react-navigation