javascript - Render async component in React Router v4

Question

I want to render a component based on the payload it receives from an api like below

<Route path="/foo/bar" render={() => {
  return (get('/some/api').then((res) => {
    return <Baz data={res.data} />
          }).catch((err) => console.log))
        }} />

But I'm getting the error:

Objects are not valid as a React child (found: [object Promise]). If you 
meant to render a collection of children, use an array instead. 

even when I do wrap Baz in []

Answer 1

unfortunately with the latest version of React - 16. Async rendering is not an option yet.

With React Router v4, the render props of Route component expects a valid React Element or array of React Elements to be returned, therefore, it doesn't accept the Promise object return from your function.

However, it's not impossible to achieve what you want with the current version of React and React Router. You just need to tweak your code a little bit. Instead of returning a Promise, your render should return a React Component, then you can do conditional rendering based on async value inside that component.

It should look like:

<Route path="/foo/bar" render={BazWrapper} />


class BazWrapper extends React.Component {

    // Do asynchronous action here
    async componentDidMount() {
       try {
          const apiValue = await get('/some/api');
          this.setState({ apiValue })
       } catch(err) {
          // error handling
       }
    }

    render() {
        const { apiValue } = this.state; 
        return <Baz data={apiValue} />;
    }

}

By calling setState after the asynchronous call finish, you let React Component know that the data is ready and it's should re-render the component.