What are the best practices for validating forms in React Final Form?

What are the best practices for validating forms in React Final Form?

When validating forms in React Final Form, it's essential to keep your validation logic simple and declarative. Use the built-in validation functions and consider using a schema validation library like Yup for complex validations.

Can you give me an example of using Yup with React Final Form?

Sure! You can create a validation schema with Yup and integrate it with React Final Form like this:

import { Form, Field } from 'react-final-form';
import * as Yup from 'yup';

const validationSchema = Yup.object().shape({
  email: Yup.string().email('Invalid email').required('Required'),
  password: Yup.string().min(6, 'Too Short!').required('Required'),
});

const onSubmit = async (values) => {
  // handle form submission
};

<Form
  onSubmit={onSubmit}
  validate={values => {
    const errors = {};
    try {
      validationSchema.validateSync(values, { abortEarly: false });
    } catch (err) {
      err.inner.forEach(error => {
        errors[error.path] = error.message;
      });
    }
    return errors;
  }}
>
  {({ handleSubmit }) => (
    <form onSubmit={handleSubmit}>
      <Field name="email" component="input" placeholder="Email" />
      <Field name="password" component="input" type="password" placeholder="Password" />
      <button type="submit">Submit</button>
    </form>
  )}
</Form>

What should I do if the validation fails?

If validation fails, you should display the error messages next to the corresponding fields. React Final Form will automatically handle the error state for you, so you can access the errors object in your form's render function and show the messages accordingly.