react-final-form

What is react-final-form?

react-final-form is a framework-agnostic form state management library for React. It provides a simple and flexible way to manage form state, validation, and submission handling in React applications.

What are react-final-form's main functionalities?

Form State Management

This feature allows you to manage the state of your form fields. The code sample demonstrates a simple form with two fields, 'firstName' and 'lastName', and a submit button. The form state is managed and displayed in real-time.

const MyForm = () => (
  <Form
    onSubmit={formValues => {
      console.log(formValues);
    }}
    render={({ handleSubmit, form, submitting, pristine, values }) => (
      <form onSubmit={handleSubmit}>
        <div>
          <label>First Name</label>
          <Field name="firstName" component="input" type="text" placeholder="First Name" />
        </div>
        <div>
          <label>Last Name</label>
          <Field name="lastName" component="input" type="text" placeholder="Last Name" />
        </div>
        <div>
          <button type="submit" disabled={submitting || pristine}>
            Submit
          </button>
        </div>
        <pre>{JSON.stringify(values, 0, 2)}</pre>
      </form>
    )}
  />
);

Field-Level Validation

This feature allows you to add validation to individual fields. The code sample shows how to add a 'required' validation to the 'firstName' and 'lastName' fields.

const required = value => (value ? undefined : 'Required');

const MyForm = () => (
  <Form
    onSubmit={formValues => {
      console.log(formValues);
    }}
    render={({ handleSubmit }) => (
      <form onSubmit={handleSubmit}>
        <div>
          <label>First Name</label>
          <Field name="firstName" component="input" type="text" placeholder="First Name" validate={required} />
        </div>
        <div>
          <label>Last Name</label>
          <Field name="lastName" component="input" type="text" placeholder="Last Name" validate={required} />
        </div>
        <div>
          <button type="submit">
            Submit
          </button>
        </div>
      </form>
    )}
  />
);

Form-Level Validation

This feature allows you to add validation to the entire form. The code sample demonstrates how to validate the 'firstName' and 'lastName' fields at the form level.

const validate = values => {
  const errors = {};
  if (!values.firstName) {
    errors.firstName = 'Required';
  }
  if (!values.lastName) {
    errors.lastName = 'Required';
  }
  return errors;
};

const MyForm = () => (
  <Form
    onSubmit={formValues => {
      console.log(formValues);
    }}
    validate={validate}
    render={({ handleSubmit }) => (
      <form onSubmit={handleSubmit}>
        <div>
          <label>First Name</label>
          <Field name="firstName" component="input" type="text" placeholder="First Name" />
        </div>
        <div>
          <label>Last Name</label>
          <Field name="lastName" component="input" type="text" placeholder="Last Name" />
        </div>
        <div>
          <button type="submit">
            Submit
          </button>
        </div>
      </form>
    )}
  />
);

Other packages similar to react-final-form

formik

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react-hook-form

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redux-form

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README

The README file is missing