How to Effectively Use Asynchronous Calls in React Render Functions?

Using Async/Await in React Render Functions: An Alternative Approach

Asynchronous programming is often encountered in React applications, particularly when dealing with external data sources. However, using async and await directly within React's render function can lead to unexpected results.

To effectively incorporate asynchronous calls in React, a common approach is to utilize state management techniques. This involves fetching data in a separate lifecycle method, such as componentDidMount or using hooks like useEffect, and updating the state once the data is available.

Consider the following example:

<code class="javascript">class ParentThatFetches extends React.Component {
  constructor() {
    this.state = { data: null };
  }

  componentDidMount() {
    fetch("/some/async/data")
      .then(resp => resp.json())
      .then(data => this.setState({ data }));
  }

  render() {
    return this.state.data ? (
      <Child data={this.state.data} />
    ) : null;
  }
}

const Child = ({ data }) => (
  <tr key={index}>
    {data.map((x, i) => (
      <td key={i}>{x}</td>
    ))}
  </tr>
);</code>

In this approach, the ParentThatFetches component fetches data asynchronously and updates its state accordingly. Once the data is available, it renders the Child component, which displays the data.

Alternative Approach: Server-Side Components

React Server Components, introduced in React 18, provide another approach for handling asynchronous data in React applications. Unlike the traditional client-side rendering model, React Server Components are rendered on the server, allowing you to fetch and process data before the HTML is sent to the client.

Here's an updated example that leverages React Server Components:

<code class="javascript">import Geocode from "react-geocode";
import _ from "lodash-es";

const getAddressData = async (getCompanyUserRidesData = []) =>
  Promise.all(
    getCompanyUserRidesData.map(async (userRides) => {
      const addr = await Geocode.fromLatLng(22.685131, 75.873468);
      const address = addr.results[0].formatted_address;
      const email = _.get(userRides, "driverId.email", "");
      const mobile = _.get(userRides, "driverId.mobile", "");
      return { address, email, mobile };
    })
  );

async function GeoServerComponent({ phase, getCompanyUserRidesData }) {
  const data = await getAddressData(getCompanyUserRidesData);
  return (
    <table>
      <tbody>
        {data.map(({ address, email, mobile }, index) => (
          <tr key={index}>
            <td>{address}</td>
            <td>Goa</td>
            <td>asdsad</td>
            <td>{email}</td>
            <td>{mobile}</td>
          </tr>
        ))}
      </tbody>
    </table>
  );
}</code>

In this example, the getAddressData function fetches the addresses asynchronously on the server. The GeoServerComponent function then receives the addresses as props and renders the necessary HTML on the server. This approach ensures that the data is ready before the HTML is sent to the client, resolving the issues encountered when using async and await directly in the render function.

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