Can’t get rid of the TypeScript error about promise-returning function as onSubmit in react-hook-form

Can’t get rid of the TypeScript error about promise-returning function as onSubmit in react-hook-form

If you are working with TypeScript and using the react-hook-form library, you may have encountered an error related to promise-returning functions as the onSubmit handler. This error typically occurs when you try to pass a promise-returning function as the onSubmit handler in react-hook-form, and TypeScript raises a type error.

Fortunately, there are a couple of solutions to this problem. Let’s explore them below:

Solution 1: Use an async wrapper function

One way to resolve the TypeScript error is to use an async wrapper function around your promise-returning onSubmit handler. This wrapper function will handle the promise and prevent TypeScript from raising the error.

Here’s an example of how you can implement this solution:

import { useForm } from 'react-hook-form';

const MyForm = () => {
  const { handleSubmit } = useForm();

  const onSubmit = async (data: FormData) => {
    // Your promise-returning logic here
    await someAsyncFunction(data);
  };

  return (
    

      {/* Form fields */}
      Submit
    
  );
};

By using the async keyword before the onSubmit function, you can safely use promise-returning logic inside the function without TypeScript raising any errors.

Solution 2: Use a type assertion

Another solution is to use a type assertion to explicitly specify the type of the onSubmit handler. This tells TypeScript that the function is a promise-returning function, and it won’t raise any errors.

Here’s an example of how you can implement this solution:

import { useForm } from 'react-hook-form';

const MyForm = () => {
  const { handleSubmit } = useForm();

  const onSubmit = (data: FormData): Promise => {
    // Your promise-returning logic here
    return someAsyncFunction(data);
  };

  return (
    

      {/* Form fields */}
      Submit
    
  );
};

By using the type assertion as any after the onSubmit function, you can explicitly specify the type as Promise, which matches the promise-returning logic inside the function.

These are two possible solutions to resolve the TypeScript error related to promise-returning functions as the onSubmit handler in react-hook-form. Choose the one that suits your coding style and preferences.

Happy coding!