I want to create a context that is actually ing from some async service (server data for example)..

//the async service to bring the context data
export const fetchContextFromAsycnService = () => {
  return  new Promise(resolve => setTimeout(
      () => resolve('Hey, im in the async context and I am the correct value'), 200)
  );
} 

class App extends Component {
  render() {
    let value = 'Im not the correct value';
    fetchContextFromAsycnService().then(x => value = x as string);
    return (
      <AsyncContext.Provider value={value}>
       <SomeComponent />
      </AsyncContext.Provider>
    );
  }
}
//user the value
export const SomeComponent = ( ) => {
  return  (
    <AsyncContext.Consumer>
     {value => <div>{value}</div>}
  </AsyncContext.Consumer>)
}
render(<App />, document.getElementById('root'));

.tsx

The expected value is: Hey, I'm in the async context and I am the correct value, but for some reason im not getting the data after it was fetched.
is there a way to create a context with

I want to create a context that is actually ing from some async service (server data for example)..

//the async service to bring the context data
export const fetchContextFromAsycnService = () => {
  return  new Promise(resolve => setTimeout(
      () => resolve('Hey, im in the async context and I am the correct value'), 200)
  );
} 

class App extends Component {
  render() {
    let value = 'Im not the correct value';
    fetchContextFromAsycnService().then(x => value = x as string);
    return (
      <AsyncContext.Provider value={value}>
       <SomeComponent />
      </AsyncContext.Provider>
    );
  }
}
//user the value
export const SomeComponent = ( ) => {
  return  (
    <AsyncContext.Consumer>
     {value => <div>{value}</div>}
  </AsyncContext.Consumer>)
}
render(<App />, document.getElementById('root'));

https://stackblitz./edit/react-ts-8zzbxa?file=index.tsx

The expected value is: Hey, I'm in the async context and I am the correct value, but for some reason im not getting the data after it was fetched.
is there a way to create a context with

• javascript
• reactjs
• react-context

1 Answer 1

but for some reason im not getting the data after it was fetched.

value is not part of the state and does not cause a re-render. Thus, you haven't seen the updated value being displayed after fetch.

To make this work, just make value part of the state to cause a re-render.

state = {
  value: 'Im not the correct value'
}

ponentDidMount() {
  // move side-effects in here
  fetchContextFromAsycnService().then(value => this.setState({ value }));
}

render() {
  return (
    <AsyncContext.Provider value={this.state.value}>
      <SomeComponent />
    </AsyncContext.Provider>
  );
}

See Demo