Solving the React Error: Objects are not valid as a React child (found: [object Promise])

Learn how to resolve the common React error when dealing with asynchronous functions and promises in your components.
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Handling Async Functions in React: Resolving the "React Child" Error

If you are working with React, you might have come across the error message: "Error: Objects are not valid as a React child (found: [object Promise])". This often happens when you attempt to directly render a promise instead of the resolved data. Understanding this issue and knowing how to fix it is crucial for building smooth and functional React applications. Let's delve into the problem and the solution in detail.

Understanding the Problem

In React, each component is expected to return a valid child element – this can be anything from a string, number, or another React component. However, when you try to use an async function directly in a React component, you risk returning a promise instead of the expected data.

Here's a simple breakdown of the situation where this error arises:

You declare a component as an async function, which is not ideal as React works synchronously when rendering components.

Inside this async function, you initiate another async function to fetch data. If not handled properly, this can lead to an undefined state where React tries to render the promise itself.

The Original Code Layout

Let's take a look at the earlier implementation which leads to the error:

[[See Video to Reveal this Text or Code Snippet]]

In this snippet, the call to start() is expected to resolve to a valid value, but since LoginScreen is declared as async, it introduces the potential for returning a promise.

Solving the Issue

Step 1: Remove Async from Component Declaration

The first and foremost thing you need to do is to remove the async keyword from the component declaration. React components should be synchronous to allow for proper rendering. Here's how you can modify the code:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Handle Async Function Calls Properly

Instead of waiting for the async function to resolve directly inside the component, you'll want to invoke it and handle its promise resolution separately. Here’s the updated version of the code:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Finalizing the Component

Finally, don't forget to include the handleSubmit which prevents the default form submission behavior:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By properly managing asynchronous operations in your React components, you can avoid the frustrating "Objects are not valid as a React child" error. Always ensure that components remain synchronous and use state to handle the resolved data from promises. This structured approach will help you build responsive and error-free applications. Happy coding!