I have an app that already uses the context api, it has a number of providers. I have added a new provider called VideoContext.
All I want is to read its activeVideo value (set elsewhere in the app)
class App extends Component {
state = {
videoState: 0,
};
setVideoState(){
//logic to alter the videoState.
}
...
render() {
return (
// Config Context
<ConfigContext.Provider value={this.decorateConfigContextFromProps()}>
<VideoContext.Provider value={this.state.videoState}>
{/* Theme Context */}
<SomeOtherProvider theme={this.decorateStyledContextFromProps()}>
{/* Redux Store Context */}
<Provider store={this.rootStore}>
<View style={{ flex: 1 }}>
<StatusBar />
<ConnectedApp />
</View>
</Provider>
</SomeOtherProvider>
</VideoContext.Provider>
</ConfigContext.Provider>
);
}
}
App.contextType = ConfigContext;
child component - miles down the tree
class DeepChild extends Component {
state = {
activeVideo: '',
};
shouldComponentUpdate(nextProps: Props, nextState) {
if (this.state.activeVideo !== nextState.activeVideo) {
return true;
}
return //otherwise do some other logic here
}
...
render() {
return (
<View/>
<VideoContext.Consumer>
/* yuck! */
{({activeVideo}) => {
if(activeVideo !== this.state.activeVideo){
this.setState({activeVideo: activeVideo}, () => {
console.log('this did indeed update the state');
})
}
}}
</VideoContext.Consumer>
<FlatList...containing many items.../>
</View>
);
}
}
How can I read the value provided by the VideoContext Provider inside the Child class component, without having to bury it inside the render function? I haven't seen any docs on this.
Thanks.
Use contextType like this
static contextType = VideoContext;
then value will be accessible like this.context.activeVideo
eg
class DeepChild extends Component {
static contextType = VideoContext;
state = {
activeVideo: '',
};
shouldComponentUpdate(nextProps: Props, nextState) {
if (this.state.activeVideo !== nextState.activeVideo) {
return true;
}
return //otherwise do some other logic here
}
...
render() {
return (
<View/>
<VideoContext.Consumer>
/* yuck! */
{({activeVideo}) => {
if(activeVideo !== this.state.activeVideo){
this.setState({activeVideo: activeVideo}, () => {
console.log('this did indeed update the state');
})
}
}}
</VideoContext.Consumer>
<FlatList...containing many items.../>
</View>
);
}
}
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.