Building Forms with ReactJS, Redux Toolkit, and Formik: A Complete Tutorial

When it comes to web development, one of the most critical features you’ll often need to implement is forms. They are the primary interface for user interaction, whether it’s a simple contact form or a complex multi-step registration form. ReactJS, a popular JavaScript library, simplifies the process of creating interactive UIs. However, dealing with complex states and forms can be challenging. This is where Redux Toolkit and Formik come into play.

Redux Toolkit is a powerful tool that simplifies state management in your ReactJS applications. It allows you to organize your app’s global state in a predictable manner, making it easier to track changes and debug your application. With Redux Toolkit, you can manage complex states that involve user interactions, network requests, and form handling, making it a go-to solution for large-scale applications.

On the other hand, Formik is a lightweight and comprehensive solution for building forms in ReactJS. It helps manage form state, validation, error handling, and submissions without the need to worry about the nitty-gritty details. Formik’s philosophy of “keeping React in React forms” makes it an excellent choice for dealing with form complexities.

Using Redux Toolkit and Formik in tandem in your ReactJS applications can greatly simplify your form building process. Redux Toolkit manages the global state and form data, while Formik takes care of form state, validation, and submissions. This combination allows for a more organized codebase, easy debugging, and efficient form handling.

In this comprehensive guide, we will delve deep into how you can leverage the power of Redux Toolkit and Formik to build efficient and robust forms in your ReactJS applications. From setting up your environment to handling complex form states and validation, we will guide you through every step of the way.

Setting Up the Environment

Before diving into form building using Redux Toolkit and Formik in ReactJS, it’s essential to set up your development environment correctly. The initial setup requires installing Node.js and Create-React-App, followed by creating a new React application.

Installing Node.js and Create-React-App

Node.js is a JavaScript runtime built on Chrome’s V8 JavaScript engine, enabling you to run JavaScript on your server or your machine. It’s a prerequisite for using ReactJS and many related tools, including Create-React-App.

To install Node.js, visit the official Node.js website and download the installer corresponding to your operating system. It’s recommended to install the LTS (Long Term Support) version for better stability.
Once Node.js is installed, you can verify the installation by running the following commands in your terminal or command prompt:

node -v
npm -v

The above commands should display the installed versions of Node.js and npm (Node Package Manager), respectively.

With Node.js installed, you can now install Create-React-App, a tool that sets up a modern web app by running one command. Install it globally using npm by running the following command in your terminal:

npm install -g create-react-app

Verify the installation of Create-React-App by checking its version:

create-react-app --version

Creating a New React Application

With Node.js and Create-React-App installed, you’re ready to create a new React application.

To create a new application, navigate to the directory where you want to create your app and run the following command in your terminal:

create-react-app redux-formik-form

This command creates a new directory named “redux-formik-form” with a new React application inside it.

Navigate into your new application’s directory:

cd redux-formik-form

Start your application:

npm start

This command starts your React application. You can now view your application by opening your web browser and navigating to http://localhost:3000.

Congratulations! You have successfully set up your development environment and created a new React application. In the following sections, we will walk you through the process of integrating Redux Toolkit and Formik into your application.

Integrating Redux Toolkit in Your ReactJS Application

Managing state in large-scale applications can be challenging. Redux Toolkit, the official, opinionated, batteries-included toolset for efficient Redux development, can significantly simplify this task. In this section, we’ll cover how to install and set up Redux Toolkit, understand its core concepts, and finally, connect it to your React application.

Installing and Setting Up Redux Toolkit

To begin integrating Redux Toolkit into your application, you first need to install the necessary package. Ensure you are in the root directory of your project and run the following command in your terminal:

npm install @reduxjs/toolkit

This command adds the Redux Toolkit to your project, making it available for use.

Understanding Redux Store, Actions, and Reducers

Before diving into the code, let’s understand some core Redux concepts:

Redux Store: The Redux Store is a JavaScript object that represents your application’s state. It’s the single source of truth that holds the entire state of your application.
Actions: Actions are plain JavaScript objects that represent what happened in the app. They must have a type field, which indicates the type of action performed.
Reducers: Reducers are functions that determine how the state should change in response to an action. They receive the current state and action, process them, and return a new state.

Connecting Redux Toolkit to Your React Application

To connect Redux Toolkit to your React application, you need to create a Redux store and provide it to your React application. Here’s how to do it:

In the src directory of your project, create a new folder named app, and inside the app folder, create a new file named store.js.
Open store.js and add the following code:

import { configureStore } from '@reduxjs/toolkit';

export default configureStore({
  reducer: {},
});

This code creates a Redux store using Redux Toolkit’s configureStore function. For now, we’re not passing any reducers to the store.

Now, open your src/index.js file and modify it as follows to provide the Redux store to your React application:

import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import store from './app/store';
import App from './App';

ReactDOM.render(
  <React.StrictMode>
    <Provider store={store}>
      <App />
    </Provider>
  </React.StrictMode>,
  document.getElementById('root')
);

The Provider component from react-redux makes the Redux store available to your React components.

With these steps, you’ve successfully integrated Redux Toolkit into your React application. In the next sections, we’ll dive into creating forms with Formik and managing their state with Redux Toolkit.

Getting Started with Formik

Formik is a small library that helps you with the three most annoying parts of form handling in React: getting values in and out of form state, validation and error messages, and form submission. Here, we’ll walk through how to install and set up Formik, followed by an overview of its essential components and functions.

Installing and Setting Up Formik

Installing Formik is a straightforward process. From your project’s root directory, run the following command in your terminal:

npm install formik

This command adds Formik to your project, making it ready for use in your forms.

An Overview of Formik’s Components and Functions

Formik provides several components and functions that simplify form handling in React. Here are a few key ones:

<Formik /> Component: This is the main Formik component that wraps your form and manages the form state. It takes initial form values, a submit handler, and a validation function as props.
<Form /> Component: This component automatically hooks into Formik’s handleSubmit and handleReset props. It’s a replacement for the standard HTML form tag.
<Field /> Component: This component is a replacement for the standard HTML input, textarea, and select tags. It automatically hooks into Formik’s context and manages form field state.
<ErrorMessage /> Component: This component displays an error message for a field when the field’s value is invalid.
useFormik() Hook: If you prefer using hooks, Formik provides the useFormik() hook, which returns an object with handlers and values needed to manage your form.

Here’s an example of a simple Formik form:

import { Formik, Form, Field, ErrorMessage } from 'formik';

function MyForm() {
  return (
    <Formik
      initialValues={{ name: '' }}
      validate={values => {
        const errors = {};
        if (!values.name) {
          errors.name = 'Required';
        }
        return errors;
      }}
      onSubmit={(values, { setSubmitting }) => {
        setTimeout(() => {
          alert(JSON.stringify(values, null, 2));
          setSubmitting(false);
        }, 400);
      }}
    >
      {({ isSubmitting }) => (
        <Form>
          <Field type="text" name="name" />
          <ErrorMessage name="name" component="div" />
          <button type="submit" disabled={isSubmitting}>
            Submit
          </button>
        </Form>
      )}
    </Formik>
  );
}

export default MyForm;

In the example above, we’ve created a simple form with one field (name). The validate function checks if the name field is empty and returns an error message if it is. On form submission, the onSubmit function alerts the form values.

With Formik installed and set up, we can now proceed to create forms using Formik and manage their state using Redux Toolkit.

Creating a Basic Form Using Formik in Your ReactJS Application

Formik simplifies the process of building, validating, and handling form submissions in React. In this section, we will guide you on creating a basic form using Formik in your ReactJS application. We’ll design the form layout, handle the form state with Formik, and validate form inputs.

Designing the Form Layout

Let’s start by creating a simple form layout. In the src directory, create a new file named ContactForm.js and add the following code:

import { Formik, Form, Field, ErrorMessage } from 'formik';

function ContactForm() {
  return (
    <Formik
      initialValues={{ name: '', email: '', message: '' }}
      // validation and submission logic goes here
    >
      {({ isSubmitting }) => (
        <Form>
          <div>
            <label htmlFor="name">Name:</label>
            <Field type="text" id="name" name="name" />
            <ErrorMessage name="name" component="div" />
          </div>
          
          <div>
            <label htmlFor="email">Email:</label>
            <Field type="email" id="email" name="email" />
            <ErrorMessage name="email" component="div" />
          </div>
          
          <div>
            <label htmlFor="message">Message:</label>
            <Field as="textarea" id="message" name="message" />
            <ErrorMessage name="message" component="div" />
          </div>

          <button type="submit" disabled={isSubmitting}>
            Submit
          </button>
        </Form>
      )}
    </Formik>
  );
}

export default ContactForm;

In this code, we’ve created a basic contact form with name, email, and message fields. Each field is associated with a label and an error message component.

Handling Form State with Formik

Formik handles the form state out of the box. We just need to provide the initial values to the Formik component. In our case, the initial values for name, email, and message fields are all empty strings.

initialValues={{ name: '', email: '', message: '' }}

Validating Form Inputs with Formik

Formik allows us to write custom validation logic for our form. We can add a validate function to the Formik component. This function receives the form values and should return an object containing error messages for the invalid fields.

Here’s an example of how to validate the inputs in our contact form:

<Formik
  initialValues={{ name: '', email: '', message: '' }}
  validate={values => {
    const errors = {};

    if (!values.name) {
      errors.name = 'Required';
    }

    if (!values.email) {
      errors.email = 'Required';
    } else if (
      !/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i.test(values.email)
    ) {
      errors.email = 'Invalid email address';
    }

    if (!values.message) {
      errors.message = 'Required';
    }

    return errors;
  }}
  // submission logic goes here
>

In this code, we’re checking if the name and message fields are empty and if the email field contains a valid email address. If any of these checks fail, we add an error message to the errors object.

With these steps, you’ve created a basic form using Formik in your ReactJS application. This form accepts user input, validates it, and is ready for the next steps, which involve managing the form’s state using Redux Toolkit and handling form submissions.

In the following sections, we’ll explain how to connect your Formik form with Redux, letting you efficiently manage your form state in a Redux store, and facilitate actions like pre-filling form fields, persisting form data, and more.

Managing Form State with Redux Toolkit

Redux Toolkit is a powerful library for managing state in React applications. It makes it easy to write Redux logic in fewer lines of code. In this section, we’ll discuss how to manage the state of a Formik form using Redux Toolkit. We’ll cover dispatching actions from form events, updating the Redux store based on these actions, and selecting form data from the Redux store.

Dispatching Actions from Form Events

The first step in managing form state with Redux Toolkit is to dispatch actions from form events. These actions represent the different changes that can occur in your form, such as updating a field, submitting the form, and resetting the form.

In Redux Toolkit, you create actions using the createSlice function, which generates action creators and action types based on the reducers you define.

Let’s add a formSlice.js file in our app folder:

// src/app/formSlice.js
import { createSlice } from '@reduxjs/toolkit';

export const formSlice = createSlice({
  name: 'form',
  initialState: {
    name: '',
    email: '',
    message: '',
  },
  reducers: {
    updateField: (state, action) => {
      state[action.payload.field] = action.payload.value;
    },
    resetForm: state => {
      state.name = '';
      state.email = '';
      state.message = '';
    },
  },
});

export const { updateField, resetForm } = formSlice.actions;

export default formSlice.reducer;

In this file, we’ve defined a form slice of our Redux store with name, email, and message fields. We’ve also defined two actions: updateField for updating a field and resetForm for resetting the form.

Updating the Redux Store Based on Form Actions

Next, we need to handle these actions in our Redux store. When an action is dispatched, Redux Toolkit automatically calls the corresponding reducer function and updates the store.

First, let’s add the form reducer to our store. Update your store.js file as follows:

// src/app/store.js
import { configureStore } from '@reduxjs/toolkit';
import formReducer from './formSlice';

export default configureStore({
  reducer: {
    form: formReducer,
  },
});

Now, whenever you dispatch the updateField or resetForm actions, Redux Toolkit will call the corresponding reducer and update the form slice of your store.

Selecting Form Data from the Redux Store

Finally, we need to select the form data from our Redux store in our React components. We can do this using the useSelector hook from react-redux.

In your ContactForm.js file, import useDispatch and useSelector from react-redux, and updateField from formSlice.js. Then, use useDispatch to get the dispatch function, and useSelector to get the form data:

import { useDispatch, useSelector } from 'react-redux';
import { updateField } from './app/formSlice';

function ContactForm() {
  const dispatch = useDispatch();
  const form = useSelector(state => state.form);

  // rest of the component
}

Now, you can dispatch the updateField action whenever a field changes, and use the form data from your Redux store in your component.

With these steps, you’ve successfully managed the state of a Formik form using Redux Toolkit. You’ve learned how to dispatch actions from form events, update the Redux store based on these actions, and select form data from the Redux store.

Integrating Redux Toolkit and Formik

In the previous sections, we separately explored Redux Toolkit for state management and Formik for form handling. Now, let’s integrate these two powerful libraries to create a robust form solution in React. We’ll cover connecting Formik with Redux to handle form state and utilizing Formik and Redux Toolkit for validation and error handling.

Connecting Formik with Redux: Handling Form State

Connecting Formik with Redux involves dispatching actions when the form state changes, and using the Redux state to control the form fields.

We’ll use the handleChange event from Formik to dispatch actions. We also need to set the initial values of the form fields from the Redux store.

Here’s how you can achieve this:

import { useDispatch, useSelector } from 'react-redux';
import { Formik, Form, Field, ErrorMessage } from 'formik';
import { updateField } from './app/formSlice';

function ContactForm() {
  const dispatch = useDispatch();
  const form = useSelector(state => state.form);

  const handleChange = (field) => (evt) => {
    dispatch(updateField({ field, value: evt.target.value }));
  }

  return (
    <Formik
      initialValues={form}
      // validation and submission logic goes here
    >
      {({ isSubmitting }) => (
        <Form>
          <div>
            <label htmlFor="name">Name:</label>
            <Field type="text" id="name" name="name" onChange={handleChange('name')} value={form.name} />
            <ErrorMessage name="name" component="div" />
          </div>

          {/* rest of the form fields */}

          <button type="submit" disabled={isSubmitting}>
            Submit
          </button>
        </Form>
      )}
    </Formik>
  );
}

export default ContactForm;

In this example, we’re using the handleChange function to dispatch the updateField action whenever a field changes. We’re also setting the initial values of the form fields from the Redux store.

Formik and Redux Toolkit for Validation and Error Handling

Formik and Redux Toolkit can also work together for validation and error handling. You can keep the form validation logic in the Formik component as before, and store the validation errors in the Redux state. This way, you can access the validation errors from anywhere in your app.

Here’s how to update the formSlice.js to handle validation errors:

// src/app/formSlice.js
import { createSlice } from '@reduxjs/toolkit';

export const formSlice = createSlice({
  name: 'form',
  initialState: {
    name: '',
    email: '',
    message: '',
    errors: {},
  },
  reducers: {
    updateField: (state, action) => {
      state[action.payload.field] = action.payload.value;
    },
    setErrors: (state, action) => {
      state.errors = action.payload;
    },
    resetForm: state => {
      state.name = '';
      state.email = '';
      state.message = '';
      state.errors = {};
    },
  },
});

export const { updateField, setErrors, resetForm } = formSlice.actions;

export default formSlice.reducer;

In this code, we’ve added an errors field to our form state, and a setErrors action to update this field. You can dispatch this action in the validate function of the Formik component to store the validation errors in the Redux state.

By integrating Redux Toolkit and Formik in this manner, you can leverage the strengths of both libraries to build robust forms in ReactJS.

Building a Complex Form with ReactJS, Redux Toolkit, and Formik

Now that we have explored how Redux Toolkit and Formik integrate, let’s dive into building a more complex form. The form we’ll build will include multiple steps, conditional fields, and field arrays. We’ll discuss defining the form structure and state, creating and dispatching actions for each form event, updating and selecting state from the Redux store, and implementing validation and error handling.

Defining the Form Structure and State

Let’s consider a multi-step registration form with the following fields:

Step 1: User details (name, email)
Step 2: Address details (street, city, state, country)
Step 3: Agreement (checkbox to agree to terms and conditions)

In the Redux store, the state for this form could be:

{
  userDetails: {
    name: '',
    email: '',
  },
  addressDetails: {
    street: '',
    city: '',
    state: '',
    country: '',
  },
  agreement: false,
  currentStep: 1,
  errors: {},
}

Creating and Dispatching Actions for Each Form Event

For each form event, you’ll need to create and dispatch an action. For instance, when a user types into the ‘name’ field, you’ll dispatch an updateUserDetails action with the field name and value. When a user navigates to the next step, you’ll dispatch a nextStep action.

These actions could be defined in your Redux slice as:

reducers: {
  updateUserDetails: (state, action) => {
    state.userDetails[action.payload.field] = action.payload.value;
  },
  updateAddressDetails: (state, action) => {
    state.addressDetails[action.payload.field] = action.payload.value;
  },
  agreeToTerms: (state, action) => {
    state.agreement = action.payload;
  },
  nextStep: (state) => {
    state.currentStep += 1;
  },
  prevStep: (state) => {
    state.currentStep -= 1;
  },
  setErrors: (state, action) => {
    state.errors = action.payload;
  },
  resetForm: state => {
    // Reset all fields
  },
}

Updating and Selecting State from the Redux Store

Using the Redux useDispatch and useSelector hooks, you can dispatch these actions and select the form data in your Formik form. The handleChange function will be slightly different for each step, and you’ll dispatch the nextStep and prevStep actions for navigation.

Implementing Validation and Error Handling

For validation, you can use the validate function in the Formik component. It receives the form values and should return an object with any errors. You can dispatch the setErrors action from this function to store the errors in the Redux state.

With these steps, you can build a complex, multi-step form using ReactJS, Redux Toolkit, and Formik. This combination offers a powerful, scalable solution for form handling in large React applications.

Testing Your Form

Ensuring that your form works correctly is crucial, especially for complex forms. Testing provides confidence that your code is working as expected, and it helps prevent regressions when you make changes to your code. In this section, we’ll discuss the tools for testing applications built with ReactJS, Redux Toolkit, and Formik. We’ll also guide you through writing and running tests.

Tools for Testing ReactJS, Redux Toolkit, and Formik Applications

There are several testing libraries you can use with ReactJS, Redux Toolkit, and Formik. Some of the most popular ones include:

Jest: Jest is a JavaScript testing framework developed by Facebook. It’s easy to set up, has a comprehensive API for synchronous and asynchronous testing, and comes with built-in support for mocking.
React Testing Library: This library provides light-weight utility functions on top of react-dom and react-dom/test-utils, making it ideal for testing React components.
Redux Mock Store: This library allows you to create a mock Redux store for testing your actions and reducers.

Writing and Running Tests

Let’s write some tests for our multi-step form. We’ll use Jest and React Testing Library.

First, we need to test if the form renders correctly:

// ContactForm.test.js
import { render } from '@testing-library/react';
import ContactForm from './ContactForm';

test('renders contact form', () => {
  const { getByLabelText } = render(<ContactForm />);
  const nameField = getByLabelText(/name/i);
  expect(nameField).toBeInTheDocument();
});

This test checks if the ‘name’ field is present in the document.

Next, we can test if the form validation works correctly. We’ll use the fireEvent function from React Testing Library to simulate user input, and then check if the validation error message is displayed:

import { render, fireEvent } from '@testing-library/react';
import ContactForm from './ContactForm';

test('shows an error when the name field is empty', () => {
  const { getByLabelText, getByText } = render(<ContactForm />);
  const nameField = getByLabelText(/name/i);
  fireEvent.change(nameField, { target: { value: '' } });
  fireEvent.blur(nameField);
  const errorMessage = getByText(/name is required/i);
  expect(errorMessage).toBeInTheDocument();
});

To run these tests, you can use the npm test command if you’re using Create React App. This command runs Jest in the interactive watch mode.

With these testing techniques, you can ensure that your form built with ReactJS, Redux Toolkit, and Formik is working correctly and providing a good user experience.

Best Practices for Building Forms with ReactJS, Redux Toolkit, and Formik

Creating robust and user-friendly forms is a critical aspect of many React applications. To ensure you’re leveraging the full power of ReactJS, Redux Toolkit, and Formik, it’s important to adhere to certain best practices. This section will highlight the importance of keeping your Redux store organized, making the most of Formik’s features, and testing as you go.

Keeping Your Redux Store Organized

When using Redux for state management, keeping your store well-structured and predictable is crucial. Here are some tips:

Normalized State: Normalizing your state means keeping your data in a flat structure, much like a database. It helps prevent data duplication and inconsistencies.
Modular Reducers: Instead of having a monolithic reducer, use Redux Toolkit’s createSlice function to create modular reducers that each handle a specific slice of the state.
Action Types: Use descriptive action types to make debugging easier. The action type should describe what is happening in the app when the action is dispatched.

Making the Most of Formik’s Features

Formik offers many features to make form handling easier:

Validation: Formik’s built-in validation can simplify your validation logic. You can provide a validation schema (with Yup, for example) or a validate function to validate the form fields.
Formik Components: Formik provides several helper components such as Field, ErrorMessage, and Form. Use these components to reduce boilerplate and make your code cleaner.
Formik Context: If you have deeply nested form fields, use the Formik context to avoid passing props down multiple levels.

Testing as You Go

When building forms, it’s a good practice to write tests as you go:

Unit Tests: Write unit tests for your actions and reducers to ensure that your Redux store is working correctly.
Component Tests: Use tools like React Testing Library to test your form components. You can test if the form renders correctly, if the validation works as expected, and if the form data is submitted correctly.
End-to-End Tests: Consider using a tool like Cypress for end-to-end testing. These tests can simulate user behavior and verify that the entire flow of your form works correctly.

By following these best practices, you can build robust, maintainable, and user-friendly forms with ReactJS, Redux Toolkit, and Formik.

Conclusion

Building forms in ReactJS applications can often be a complex task, especially when dealing with large forms with many fields and validation rules. In this comprehensive guide, we’ve explored how to simplify this task by using Redux Toolkit for state management and Formik for form handling.

We started by setting up the environment and integrating Redux Toolkit into your ReactJS application. We then introduced Formik and demonstrated how to create a basic form. From there, we discussed managing form state with Redux Toolkit, followed by integrating Redux Toolkit and Formik. We also delved into building a complex form, testing your form, and shared some best practices for building forms with ReactJS, Redux Toolkit, and Formik.

Formik simplifies form handling in ReactJS, providing a range of features such as form state management, validation, and error handling. Redux Toolkit, on the other hand, offers a set of tools that make it easier to write Redux logic, manage global state, and perform complex state transformations.

By integrating these two powerful libraries, you can create robust, maintainable, and user-friendly forms in your ReactJS applications. Remember to keep your Redux store organized, make the most of Formik’s features, and test your forms as you go. This will not only ensure that your forms work correctly, but it will also lead to more maintainable and less error-prone code.

As you continue on your journey with ReactJS, Redux Toolkit, and Formik, keep exploring, learning, and experimenting. The world of web development is continually evolving, and there’s always more to learn.