redux-form

What is redux-form?

redux-form is a library that allows you to manage form state in Redux. It provides a way to keep form state in a Redux store, making it easier to manage complex forms and their validation, submission, and other behaviors.

What are redux-form's main functionalities?

Form Creation

This code demonstrates how to create a simple form using redux-form. The `Field` component is used to define form fields, and the `reduxForm` higher-order component is used to connect the form to Redux.

import React from 'react';
import { Field, reduxForm } from 'redux-form';

let SimpleForm = props => {
  const { handleSubmit } = props;
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="firstName">First Name</label>
        <Field name="firstName" component="input" type="text" />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};

SimpleForm = reduxForm({
  form: 'simple'
})(SimpleForm);

export default SimpleForm;

Form Validation

This code demonstrates how to add validation to a form using redux-form. The `validate` function checks for errors and returns an object with error messages, which are then used by redux-form to display validation errors.

import React from 'react';
import { Field, reduxForm } from 'redux-form';

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

let ValidatedForm = props => {
  const { handleSubmit } = props;
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="firstName">First Name</label>
        <Field name="firstName" component="input" type="text" />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};

ValidatedForm = reduxForm({
  form: 'validated',
  validate
})(ValidatedForm);

export default ValidatedForm;

Form Submission

This code demonstrates how to handle form submission using redux-form. The `handleSubmit` function is passed a `submit` function that processes the form data.

import React from 'react';
import { Field, reduxForm } from 'redux-form';

const submit = values => {
  console.log('Form data:', values);
};

let SubmitForm = props => {
  const { handleSubmit } = props;
  return (
    <form onSubmit={handleSubmit(submit)}>
      <div>
        <label htmlFor="firstName">First Name</label>
        <Field name="firstName" component="input" type="text" />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};

SubmitForm = reduxForm({
  form: 'submit'
})(SubmitForm);

export default SubmitForm;

Other packages similar to redux-form

formik

Formik is a popular form library for React that provides a simpler API compared to redux-form. It focuses on reducing boilerplate and improving performance by not relying on Redux for form state management. Formik is often preferred for its ease of use and flexibility.

react-hook-form

React Hook Form is a library that uses React hooks to manage form state and validation. It is known for its minimal re-renders and high performance. Unlike redux-form, it does not require Redux and is often chosen for its simplicity and performance benefits.

final-form

Final Form is a framework-agnostic form state management library that can be used with React through the react-final-form package. It offers similar functionality to redux-form but is designed to be more lightweight and flexible, without the need for Redux.

README

#redux-form

redux-form works with React Redux to enable an html form in React to use Redux to store all of its state.

Installation

npm install --save redux-form

Benefits

Why would anyone want to do this, you ask? React a perfectly good way of keeping state in each component! The reasons are threefold.

Unidirectional Data Flow

For the same reason that React and Flux is superior to Angular's bidirectional data binding. Tracking down bugs is much simpler when the data all flows through one dispatcher.

Redux Dev Tools

When used in conjunction with Redux Dev Tools, you can fast forward and rewind through your form data entry to better find bugs.

Stateless Components

By removing the state from your form components, you inherently make them easier to understand, test, and debug. The React philosophy is to always try to use props instead of state when possible.

How it works

When you are adding your reducers to your redux store, add a new one with createFormReducer(]).

import { createStore, combineReducers } from 'redux';
import { createFormReducer } from 'redux-form';
const reducers = {
  // ... your other reducers here ...
  createFormReducer('contactForm', ['name', 'address', 'phone'])
}
const reducer = combineReducers(reducers);
const store = createStore(reducer);

reduxForm() creates a Higher Order Component that expects a dispatch prop and a slice of the Redux store where its data is stored as a form prop. These should be provided by React Redux's connect() function.

Let's look at an example:

Then, on your form component, add the @reduxForm('contactForm') decorator.

import React, {Component, PropTypes} from 'react';
import {connect} from 'react-redux';
import reduxForm from 'redux-form';
import contactValidation from './contactValidation';

class ContactForm extends Component {
  // you don't need all to define all these props,
  // only the ones you intend to use
  static propTypes = {
    data: PropTypes.object.isRequired,
    dirty: PropTypes.bool.isRequired,
    errors: PropTypes.object.isRequired,
    handleBlur: PropTypes.func.isRequired,
    handleChange: PropTypes.func.isRequired,
    handleSubmit: PropTypes.func.isRequired,
    initializeForm: PropTypes.func.isRequired,
    invalid: PropTypes.bool.isRequired,
    pristine: PropTypes.bool.isRequired,
    resetForm: PropTypes.func.isRequired,
    touch: PropTypes.func.isRequired,
    touched: PropTypes.object.isRequired,
    touchAll: PropTypes.func.isRequired,
    untouch: PropTypes.func.isRequired,
    untouchAll: PropTypes.func.isRequired,
    valid: PropTypes.bool.isRequired
  }
  
  render() {
    const {
      data: {name, address, phone},
      errors: {name: nameError, address: addressError, phone: phoneError},
      touched: {name: nameTouched, address: addressTouched, phone: phoneTouched},
      handleBlur,
      handleChange,
      handleSubmit
    } = this.props;
    return (
      <form onSubmit={handleSubmit}>
        <label>Name</label>
        <input type="text" 
               value={name} 
               onChange={handleChange('name')} 
               onBlur={handleBlur('name')}/>
        {nameError && nameTouched ? <div>{nameError}</div>}
        
        <label>Address</label>
        <input type="text" 
               value={address} 
               onChange={handleChange('address')} 
               onBlur={handleBlur('address')}/>
        {addressError && addressTouched ? <div>{addressError}</div>}
        
        <label>Phone</label>
        <input type="text" 
               value={phone} 
               onChange={handleChange('phone')} 
               onBlur={handleBlur('phone')}/>
        {phoneError && phoneTouched ? <div>{phoneError}</div>}
        
        <button onClick={handleSubmit}>Submit</button>
      </form>
    );
  }
}

// apply reduxForm() and include synchronous validation
ContactForm = reduxForm('contactForm', contactValidation)(ContactForm);

// ------- HERE'S THE IMPORTANT BIT -------
function mapStateToProps(state) {
  return { form: state.contactForm };
}
// apply connect() to bind it to Redux state
ContactForm = connect(mapStateToProps)(ContactForm);

// export the wrapped component
export default ContactForm;

Notice that we're just using vanilla <input> elements there is no state in the ContactForm component. I have left handling onSubmit as an exercise for the reader. Hint: your data is in this.props.data.

Binding Action Creators

If your form component also needs other redux action creators - and it probably does since you need to submit somehow - you cannot simply use the default bindActionCreators() from redux, because that will remove dispatch from the props the connect() passes along, and reduxForm needs dispatch. You will need to also include dispatch in your mapDispatchToProps() function. Like so:

import {bindActionCreators} from `redux`;

...

function mapDispatchToProps(dispatch) {
  return bindActionCreators(actionCreators, dispatch);
}

ContactForm = connect(mapStateToProps, mapDispatchToProps)(ContactForm);

to:

import {bindActionCreators} from `redux`;

...

function mapDispatchToProps(dispatch) {
  return {
    ...bindActionCreators(actionCreators, dispatch),
    dispatch
  };
}

ContactForm = connect(mapStateToProps, mapDispatchToProps)(ContactForm);

ES7 Decorator Sugar

Using ES7 decorator proposal, the example above could be written as:

@connect(state => ({ form: state.contactForm }))
@reduxForm('contactForm', contactValidation)
export default class ContactForm extends Component {

Much nicer, don't you think?

You can enable it with Babel Stage 1. Note that decorators are experimental, and this syntax might change or be removed later.

Synchronous Validation

You may optionally supply a validation function, which is in the form ({}) => {} and takes in all your data and spits out error messages as well as a valid flag. For example:

function contactValidation(data) {
  const errors = { valid: true };
  if(!data.name) {
    errors.name = 'Required';
    errors.valid = false;
  }
  if(data.address && data.address.length > 50) {
    errors.address = 'Must be fewer than 50 characters';
    errors.valid = false;
  }
  if(!data.phone) {
    errors.phone = 'Required';
    errors.valid = false;
  } else if(!/\d{3}-\d{3}-\d{4}/.test(data.phone)) {
    errors.phone = 'Phone must match the form "999-999-9999"'
    errors.valid = false;
  }
  return errors;
}

You get the idea.

You must return a boolean valid flag in the result.

Asynchronous Validation

Async validation can be achieved by calling an additional function on the function returned by reduxForm() and passing it an asynchronous function that returns a promise that will resolve to validation errors of the format that the synchronous validation function generates. So this...

// apply reduxForm() and include synchronous validation
ContactForm = reduxForm('contactForm', contactValidation)(ContactForm);

...changes to this:

function asyncValidation(data) {
  return new Promise((resolve, reject) => {
    const errors = {valid: true};
    // do async validation
    resolve(errors);
  });
}

// apply reduxForm() and include synchronous AND asynchronous validation
ContactForm = reduxForm('contactForm', contactValidation)
  .async(asyncValidation)(ContactForm);

Optionally, if you want asynchronous validation to be triggered when one or more of your form fields is blurred, you may pass those fields to the async() function along with the asynchronous validation function. Like so:

ContactForm = reduxForm('contactForm', contactValidation)
  .async(asyncValidation, 'name', 'phone')(ContactForm);

With that call, the asynchronous validation will be called when either name or phone is blurred. Assuming that they have their onBlur={handleBlur('name')} properties properly set up.

NOTE! If you only want asynchronous validation, you may leave out the synchronous validation function. And if you only want it to be run on submit, you may leave out the fields, as well.

ContactForm = reduxForm('contactForm').async(asyncValidation)(ContactForm);

API

Each form has a sliceName. That's the key in the Redux store tree where the data will be mounted.

createFormReducer(sliceName:string, fields:Array<string>, config:Object?)

-sliceName : string

the name of your form and the key to where your form's state will be mounted in the Redux store

- fields : Array<string>

a list of all your fields in your form.

-config: Object [optional]

some control over when to mark fields as "touched" in the form:

config.touchOnBlur : boolean [optional]

marks fields to touched when the blur action is fired. defaults to true

config.touchOnChange : boolean [optional]

marks fields to touched when the change action is fired. defaults to false

reduxForm(sliceName:string, validate:Function?)

-sliceName : string

the name of your form and the key to where your form's state will be mounted in the Redux store

-validate : Function [optional]

your synchronous validation function. Defaults to () => ({valid: true})

reduxForm().async(asyncValidate:Function, ...fields:String?)

-asyncValidate : Function

a function that takes all the form data and returns a Promise that will resolve to an object of validation errors in the form { field1: <string>, field2: <string>, valid: <boolean> } just like the synchronous validation function. See Aynchronous Validation for more details.

-...fields : String [optional]

field names for which handleBlur should trigger a call to the asyncValidate function

props

The props passed into your decorated component will be:

-asyncValidate : Function

a function that may be called to initiate asynchronous validation if asynchronous validation is enabled

-asyncValidating : boolean

true if the asynchronous validation function has been called but has not yet returned.

-data : Object

The form data, in the form { field1: <string>, field2: <string> }

-dirty : boolean

true if the form data has changed from its initialized values. Opposite of pristine.

-errors : Object

All the errors, in the form { field1: <string>, field2: <string> }

-handleBlur(field:string) : Function

Returns a handleBlur function for the field passed.

-handleChange(field:string) : Function

Returns a handleChange function for the field passed.

-handleSubmit : Function

a function meant to be passed to <form onSubmit={handleSubmit}> or to <button onClick={handleSubmit}>. It will run validation, both sync and async, and, if the form is valid, it will call this.props.onSubmit(data) with the contents of the form data.

Optionally, you may also pass your onSubmit function to handleSubmit which will take the place of the onSubmit prop. For example: <form onSubmit={handleSubmit(this.save.bind(this))}>

-initializeForm(data:Object) : Function

Initializes the form data to the given values. All dirty and pristine state will be determined by comparing the current data with these initialized values.

-invalid : boolean

true if the form has validation errors. Opposite of valid.

-pristine: boolean

true if the form data is the same as its initialized values. Opposite of dirty.

-resetForm() : Function

Resets all the values in the form to the initialized state, making it pristine again.

-touch(...field:string) : Function

Marks the given fields as "touched" to show errors.

-touched : Object

the touched flags for each field, in the form { field1: <boolean>, field2: <boolean> }

-touchAll() : Function

Marks all fields as "touched" to show errors. should be called on form submission.

-untouch(...field:string) : Function

Clears the "touched" flag for the given fields

-untouchAll() : Function

Clears the "touched" flag for the all fields

-valid : boolean

true if the form passes validation (has no validation errors). Opposite of invalid.

Submitting your form

The recommended way to submit your form is to create your form component as shown above, using the handleSubmit prop, and then pass an onSubmit prop to your form component.

import React, {Component, PropTypes} from 'redux-form';
import {connect} from 'redux';
import {initialize} from 'redux-form';

class ContactPage extends Component {
  static propTypes = {
    dispatch: PropTypes.func.isRequired
  }
  
  handleSubmit(data) {
    console.log('Submission received!', data);
    this.props.dispatch(initialize('contactForm', {})); // clear form
  }
  
  render() {
    return (
      <div>
        <h1>Contact Information</h1>
        
        <ContactForm onSubmit={this.handleSubmit.bind(this)}/>
      </div>
    );
  }
}

export default connect()(ContactPage);  // adds dispatch prop

Or, if you wish to do your submission directly from your decorated form component, you may pass a function to handleSubmit. To abbreviate the example shown above:

class ContactForm extends Component {
  static propTypes = {
    // ...
    handleSubmit: PropTypes.func.isRequired
  }
  
  saveForm(data) {
    // make server call to save the data
  }
  
  render() {
    const {
      // ...
      handleSubmit
    } = this.props;
    return (
      <form onSubmit={handleSubmit(this.saveForm)}> // <--- pass saveForm
        // ...
      </form>
    );
  }
}

Responding to other actions

Part of the beauty of the flux architecture is that all the reducers (or "stores", in canonical Flux terminology) receive all the actions, and they can modify their data based on any of them. For example, say you have a login form, and when your login submission fails, you want to clear out the password field. Your login submission is part of another reducer/actions system, but your form can still respond.

Rather than just using the vanilla reducer function generated by createFormReducer(), you can augment it to do other things.

import {createFormReducer} from 'redux-form';
import {AUTH_LOGIN_FAIL} from '../actions/actionTypes';
const loginFormReducer = createFormReducer('loginForm', ['email', 'password']);

export default function loginForm(state, action = {}) {
  switch (action.type) {
    case AUTH_LOGIN_FAIL:
      return {
        ...state,
        data: {
          ...state.data,
          password: ''
        }
      };
    default:
      return loginFormReducer(state, action);
  }
}

Running Example

Check out the react-redux-universal-hot-example project to see redux-form in action.

This is an extremely young library, so the API may change. Comments and feedback welcome.