How to return data from Tanstack React Query useMutation?

When using the useMutation hook from Tanstack React Query, you can manage asynchronous operations and retrieve data returned from the mutation. The useMutation hook is specifically designed for operations that modify server data, such as adding, updating, or deleting data.

Using useMutation

First, define an asynchronous function that performs the actual operation, such as making network requests. Then pass this function to useMutation.

javascript
import { useMutation } from 'react-query';

const updateUser = async (userData) => {
  const response = await fetch('/update-user', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(userData),
  });

  if (!response.ok) {
    throw new Error('Network response was not ok');
  }

  return response.json(); // Returns the updated user data
};

function UserProfile({ userId }) {
  const { mutate, data, error, isSuccess, isError } = useMutation(updateUser);

  const handleSubmit = (userData) => {
    mutate(userData);
  };

  if (isSuccess && data) {
    console.log('User update successful:', data);
  }

  if (isError) {
    console.error('Update failed:', error);
  }

  return (
    <div>
      <form onSubmit={handleSubmit}>
        {/* Form content */}
      </form>
      {isSuccess && <p>User update successful!</p>}
      {isError && <p>Update failed: {error.message}</p>}
    </div>
  );
}

Important Return Values

• mutate function: This function triggers the asynchronous mutation. Call it by passing the required parameters, which are then forwarded to your asynchronous function.
• data: This holds the data returned by the asynchronous function upon successful completion. In the example above, data contains the updated user information from the server.
• error: This contains the error information if the asynchronous function throws an error or the request fails.
• isSuccess: A boolean indicating whether the mutation operation completed successfully.
• isError: A boolean indicating whether an error occurred during the mutation operation.

Usage Scenario Example

Assume you have a user profile component where users can update their information. When the user submits the form, call the mutate function and pass the new user data. Using useMutation allows you to handle loading, success, and error states directly within the component, resulting in a smoother user experience.

This provides a basic overview of handling and returning data with React Query's useMutation. We hope this helps you understand how to implement it in your projects.