Taming forms with React and Formik

In my last blog post, I was talking about redux-sagas, how cool they are and why I like them. That was a year ago. A lot has changed since then. Right now, everyone’s hooked on React hooks 🙂, and I’m on a new team working on cool stuff.

The web app I currently work on has a lot of user interaction, mainly capturing data and going on different journeys based on different products or data they are capturing. Capturing data means forms, forms everywhere!

In general, building forms is simple, you have input fields, dropdowns & radio buttons. You have some sort of validation and submit to some API endpoint.

For simple applications (pet projects), this is easy to do. However, on large-scale applications, how do you go about building these forms? There’s probably a lot of great ways to go about doing this, however, since this my blog I want to share a way in which we solved it within our team.

To help me tell the story I will be using a time booking web app called “Time with Tom“. Tom is a popular guy and therefore everyone wants to book time with Tom. This web app allows Tom to manage all his social interaction.

  1. Users can access Tom’s schedule, and they can see when Tom is available for bookings.
  2. Then users can capture a booking request with the following:
    • date
    • time
    • an activity they want to do with Tom
    • name
    • surname
    • email

Making a booking

Time with Tom uses the following:

  • React
  • Formik
  • React-Router
  • React Material-ui

Our focus is Formik.

What is Formik?
Formik is a React package which helps you build forms in React. The Formik slogan is: Build forms in React, without the tears.
More info.

In addition, I recommend doing the simple Formik tutorial on the getting started page.

The basic design for this form would look like this:

This basic design would be okay for a pet project but on a larger-scale application, this would be difficult to scale.

When you look at this form, it may be split into the following groupings:

  • User
  • Activity
  • Booking

From these groups you may create React Components from them:

  • <User />
  • <Activity />
  • <Booking />

And if you continue to iterate over this design you can create a Formik Workflow.

What is a Formik Workflow?

Its a Factory Function that always returns an object with the following:

  • A Component function
  • A payload function
  • A validate function
  • A isActive function
  • A initialValues object literal

File: UserWorkflowFactory

import React from 'react';
import User from './component';
import payload from './payload';
import validate from './validate';
import initialValues from './initial-values';
import isActive from './active';

 * User Workflow Factory
 * @param {Object} options
 * @return {Workflow}
const UserWorkflowFactory = ({ ...options }) => {
  return {
    Component: () => <User />,
    payload: (values) => payload(values),
    validate: (values) => validate(values),
    isActive: (values) => isActive(values),

export default UserWorkflowFactory;

Component (Component)

The component is a React component, that houses all the Formik fields for the current workflow. Example User component with Formik fields for:

  • Name
  • Surname
  • Email

Example: <User /> Component
Note: The Component will always use FormikContext to get the values of the fields for the component. FormikContext uses React’s Context API.

Payload (payload)
The payload function extracts the workflow values from the Formik values object. This is used when submitting the Formik form.

Example: payload function
Note: The payload function will always be called with the Formik values object.

Validate (validate)
The validate function validates the current workflow values. Example if User fields are empty. The validate function will return an object with required fields errors.

Example: validate function
Note: The validate function will always be called with the Formik values object.

Is Active (isActive)

The isActive function acts as the business logic section. In this section, we may use whatever logic or data to verify whether our Formik workflow should be active. This will be used by Formik to check whether it needs to do the following for the workflow:

  • display the workflow component with its fields
  • do validation on the workflow
  • or get the mapped payload for the workflow.

Note: The isActive function will always be called with the Formik values object.

Initial Values (initialValues)

The initialValues object literal initialises the Formik form with the workflow fields. Example User fields are:

  • name
  • surname
  • email

Example: initialValues
Note: The initialValues object literal fields are used in all the workflow functions, and React component (payload, validate, Component and isActive).

Benefits of Formik Workflow:

  • Separation of concerns
  • Easy to make changes
  • Easy to tests
  • The payload function can have tests to ensure it’s producing the expected mapped payload.
  • The validate function can also have tests to ensure that the workflow validates correctly.
  • The isActive function can also have tests to ensure that the workflow business rules are correct.

Now with these Formik workflows, how would we use them? You can think of a group of Formik workflows as a feature or Formik Feature.

Time with Tom has a “Booking Request” Formik Feature, which includes the following workflows:

  • Activity Workflow
  • User Workflow
  • Booking Workflow

The BookingRequestFormik feature initialises the Formik form with these workflows.

Example BookingRequestFormik feature workflows are:
File: BookingRequestFormik

const ActivityWorkflow = ActivityWorkflowFactory({});
const UserWorkflow = UserWorkflowFactory({});
const BookingWorkflow = BookingWorkflowFactory({});

const workflows = [ActivityWorkflow, UserWorkflow, BookingWorkflow];

What makes this possible is the following Formik Workflow helpers:

  • getInitialValues function
  • validateWorkflows function
  • buildPayload function

Get Initial Values (getInitialValues)
This takes in Formik workflows array. This is an array of all the initialised Formik workflows for the feature.

It takes all initialValues for each Formik workflow and returns merged initialValues object literal for Formik.

File: getInitialValues

 * get initial values from workflow and sub-worfklow for formik formik
 * @param {Workflow[]} workflows
 * @return {Object} initialValues
export default function getInitialValues(workflows) {
  return workflows
    .map((workflow) => ({ ...workflow.initialValues }))
    .reduce((previousValue, initialValues) => ({

Validate Workflows (validateWorkflows)
This takes in Formik workflows array as well. For each Formik workflow, it calls each validate function with the latest Formik values. The validate function gets called by Formik during the validation.

File: validateWorkflows

 * Validate workflows in parallel
 * @param {Workflow[]} workflows
 * @return {function(Object): Object}
const validateWorkflows = (workflows) => async (values) => {
  const errors = await Promise.all(
      .filter((workflow) => workflow.isActive(values))
      .map((workflow) => ({ ...workflow.validate(values) })),

  return errors.reduce((previousErrors, errors) => ({

export default validateWorkflows;

Build Payload (buildPayload)
This takes in Formik workflows array as well. For each Formik workflow, it calls each payload function with the latest Formik values. This is called by Formik on submit.

File: buildPayload

 * Build payload for all workflows in parallel
 * @param {Workflow[]} workflows
 * @return {function(Object): Object}
const buildPayload = (workflows) => async (values) => {
  const payload = await Promise.all(
      .filter((workflow) => workflow.isActive(values))
      .map((workflow) => ({ ...workflow.payload(values) })),

  return payload.reduce((previousPayload, currentPayload) => ({

export default buildPayload;

So when it comes together, a user can book an activity with Tom. If things stay the same then that’s it we are done and this would be the end of this post. However, as we all know in software things always change, therefore we build software to anticipate change and be able to accommodate these changes.

In Software things always change

Tom has decided that for people to book activities with him, they must pay. If you think of this from a large-scale application perspective you would have to consider the following:

  • how to add a payment Formik workflow to the existing booking request feature?
  • or do you create a new booking request feature with a payment Formik workflow as well?

Whichever method you go with, the neat thing is you know that the existing workflows (User, Activity and Booking) have been working fine. So adding the Payment Formik workflow should be as easy as adding a new component.

I’ve decided to create a payment Formik workflow and add it to the existing booking request feature. By doing this, we may also see how features may have their own business rules and how they implement those rules with Formik workflows who are not aware of these rules and simply do whatever they were built to do.

So it turns out Tom only wants to charge for some activities not all of them. This is quite easy to solve, we can just hide the Payment Formik workflow based on this business rule and show a message advising the user that the selected activity requires no payment.

Using Formik context we can retrieve the current values and using those values to validate our business rules. This is an example of the Payment Formik workflow business rule using Formik values to determine if the Payment Formik workflow is active.

File: Payment isActive

import getActivityAmount from '../../activity/util';

 * The isActive acts as the business logic section. In this section we may use whatever logic or data to
 * verify whether our payment-form should be active. This will be used by formik to check whether it needs to do
 * the following for the workflow:
 *  - display the workflow component with its fields
 *  - do the validation
 *  - get the payload
 *  Business Rule(s):
 *  1) Only display payment for paid activities - where amount is greater 0 (all paid items)
 *  2) Do NOT collect payment for free activities - where amount is 0
 * @return {boolean}
const isActive = (values) => getActivityAmount(values) > 0;

export default isActive;

Just as easy as that the booking request will now only show payment options if the activity is a paid one.

Tom is happy as we have met his requirements for only charging for these activities: Golf, Tennis, and Cycling. While Squash and Trail run activities remain free.

Making a booking final with Payment section

Using Formik workflows you get structured modules, which you may plug and play as you please. You may also create sub-workflows as long as you keep the same workflow signature. Are there other ways of taming forms? Please do share with me by kindly sending an email or connecting with me on Github. Thank you.

Source code: https://github.com/zulucoda/time-with-tom
Demo: https://time-with-tom.mfbproject.co.za/booking-request

My Current Software Development Tool-belt

My Current Software Development Tool-belt / workflow (zulucoda)

I haven’t done this before where I post about what is currently in my development tool-belt. Within these last couple years of React development from 2016 to now, I’ve grown a lot, and I’ve worked with great tools, coding techniques and different patterns. You may check out this article where I explore patterns for migrating a legacy SPAs to React.

My mission with this blog post is to show you my current development tool-belt for creating a new web application:

  • What core technology do I use and why?
  • What packages do I use and why?
  • How do I structure my code and why?

Starting with the Core Technology
My coding core technology is JavaScript.
Why JavaScript?
From 2005 to 2012 I use to build web applications (monoliths) using ASP.NET. In 2013 I made the switch to start separating my Back-end from my Front-end by using AngularJs for my Front-end. This switch gave me the ability to unit test my Front-end. The Back-end became a simple REST API that could be consumed by other applications as well, example Mobile Apps. It was also far more comfortable to code Web Apps in AngularJS using JavaScript, and I was hooked on JavaScript for everything. It was around this time I also started experimenting with nodejs (However, that’s for another blog post in the future. Back to my current development tool-belt)

So fast-forward to now; JavaScript keeps getting better and better, the community keeps creating amazing open source technologies for us to use. The ECMAScript Wizards keep adding new features and keep making JavaScript great.

My web-app core technology is React.
Why React?
I’ve invested in books, front-end masters courses and many many more hours spent on blogs and tutorials. I’ve also been using it at work since 2017 till now. I know the ins and outs of React quite well, and with React you’ve got React Native as well which allows you to do mobile apps. At the moment React is my default front-end tool, and until something comes along that’s going to dethrone React as React did with Angularjs then I might consider it, but for now, its all React for me.

Okay, great so at this point, I am using JavaScript and React.
When I start a new project, I use create-react-app.

create-react-app is a React boilerplate for more info go to https://github.com/facebook/create-react-app

$ npx create-react-app zulucoda-tool-belt-app --typescript

Why I use create-react-app?
I use it for everything. When I need to create a prototype to verify a package or feature quickly. By default it has all the basics you need:

Now that I have my core and project created, What packages do I use and why?

I am separating these into production dependencies (packages needed by the web-app to run in production) and development dependencies (excellent packages which make my development workflow superb)

Production Dependencies
Redux for State Management – https://github.com/reduxjs/redux & https://github.com/reduxjs/react-redux
Why Redux?
Once you understand the Redux architecture you, always want to create an application using this architecture. more info, please see how I use redux on migrating a legacy SPA.

$ yarn add redux react-redux

Redux-Sagas for Side Effects/Middleware – https://github.com/redux-saga/redux-saga
Why Redux-Sagas?
I use to use Redux-Thunk for Redux side effects/middleware. However, a while back a colleague of mine Mateusz Bosek introduced me to Redux-Sagas, and the Redux-Sagas pattern is terrific. Check out this article where I used sagas for migrating a legacy SPA to React.

$ yarn add redux-saga

React-Intl for Internationalising – https://github.com/yahoo/react-intl
Why React-Intl?
Before moving to Dubai, UAE. This package would not be on the list because all applications I worked on in South Africa only supported the English language, therefore, there was no need for React-Intl. However, this was just a lazy design because what if we did want to support an additional language we would have to refactor the entire application. So right now any application I work with has React-Intl by default even if only one language is used, at the start. If I need to add additional language support, the application is ready to support that.

$ yarn add react-intl

Material-ui for UI (Layout, Theme and Styling Components) – https://github.com/mui-org/material-ui
Why Material-ui?
There’s a massive community behind this open source project. React components that implement Google’s Material Design.

$ yarn add @material-ui/core

Development Dependencies
Because I used create-react-app to set up my React development. I already have the following:

  • Jest – for unit testing. I update my package.json file by setting the unit test code coverage.
  • Typescript – for type checking (In 2019 you must add types to your code.)

Update package.json

"jest": {
    "coverageThreshold": {
      "global": {
        "branches": 100,
        "functions": 100,
        "lines": 100,
        "statements": 100

Other development dependencies that help me with my development workflow:

Enzyme – https://github.com/airbnb/enzyme
why Enzyme?
I use it for unit testing React components (the view). I test things like button clicks, trigger onChange events, etc… I aim to have to have 100% test coverage in my React applications. See this blog post on unit testing in React.

$ yarn add -D enzyme enzyme-adapter-react-16

Prettier – for code format. https://github.com/prettier/prettier
Why Prettier?
No one has time to format their code :D, therefore, let prettier format your code for you. Decide your format rules upfront and let prettier do all the work. I configure prettier with husky and lint-staged to automatically format every file I commit. Therefore all code committed to GitHub is formatted automatically by prettier.

$ yarn add -D prettier husky lint-staged

Setup in package.json file

  "lint-staged": {
    "*.{js,jsx,ts,tsx}": [
      "node_modules/.bin/prettier  --config .prettierrc --write",
      "git add"
  "husky": {
    "hooks": {
      "pre-commit": "lint-staged"

Create .prettierrc file

    "singleQuote": true,
    "trailingComma": "all"

Okay, so now that I covered my core, and my main production and development packages. Next on the list is the coding structure.
With this fantastic React development environment set up with these main packages, and unit test coverage setup. All is useless if the coding structure is not modular or lacks a good structure that can scale.

Folder structure


config folder
This is where I set up my root reducers, sagas, etc.


modules folder
The modules folder is where I create my features for my web-app. Each feature has a components, containers and pages folder. Regarding nesting, before I’ve had a situation where I went crazy with nesting components inside components, this resulted in a complex nesting and over time the structure became difficult to work use. So the rule I use now, is I don’t go past 1 level of nesting. This means in the parent components is on the same level as children components. At first, this seems weird over time, and I got used to it. The same rule applies to containers and pages.


shared folder
In the shared folder, I place all items which are common or used in multiple places. This also where I place the API interface as well. The same nesting rules apply for shared folder structure.


Currently, this is I what use and its working for me. However, this is not cast in stone; it’s like an evolving style guide. Additionally, the packages and patterns that I am using are working for me right now, once again when I come across a package or patterns which works better or easier, I evaluate it, try it out and then it gets added to my tool-belt.
Repo: https://github.com/zulucoda/zulucoda-tool-belt-app

Yet Another Reason Why You Should Migrate Your Current (Legacy) SPA to React

Hybrid app solution simple overview

So with this post, I am trying something different. I am just going to tell you about my experience thus far with taking an existing SPA created in Backbone + jQuery and migrating this SPA to React.

I am going to get straight into it, and therefore if you’re new to React, my suggestion would be to check out other blog posts as this will cover advanced topics.

Additionally, I know that many people have written articles & posted videos on such migration. However, when I was reading and watching those videos, I was still missing critical architectural info. So even though sample code and blog post example were made available to me, this still didn’t help me in what I needed to do.

Migration Planning Phase
After doing research, I presented a few ideas to my colleagues and Head of Development. There where two main ways of going about our migration:

  • Hybrid Solution
  • Complete Clean Refactor

Hybrid Solution
This would allow us to slowly migrate sections of our existing Legacy SPA over to React one feature at a time. The ability for React to run side by side with other JavaScript libraries/frameworks is a significant feature. This is something I completely missed, even though Facebook have always stressed this point about React’s abilities (more on this later).

Complete Clean Refactor
We start from the ground up and re-build everything. There’s a point in the life of a product where a complete clean refactor is not feasible. When you have a product that is successful and clients are happy. Yes, the underlying tech might be outdated, it might take longer to deliver new features and maybe its no-longer developer friendly.
Additionally, asking business just for a budget to refactor an existing product? It’s no wonder why business does not trust its tech people.

After presenting this information to the team, the Hybrid Solution was a clear winner.

Before joining the team, I had been working on a React SPA that used a NodeJs + Express API. I was working on both of these code bases. Additionally, we had a React Native application using the same API. Moreover, before that, I was working on an Angularjs (1.5) App. Therefore I had no Backbone experience. However, this would not be an issue.

So we had an idea that we should do a hybrid solution, but we didn’t know how we would do it? Therefore it was suggested that we start by prototyping this hybrid solution.

The Prototype Phase
This phase would last two weeks, and we would use the learning’s from this phase to create an architectural solution, which we will use going forward for our smooth react migration.

During this prototype phase, I tried many solutions to get React working side by side with the Legacy SPA. Going back to the statement above about React being able to run side by side with other JavaScript libraries, I completely missed this in the first week of prototyping. I had created a complex solution evolving an iframe which would run the React app in the iframe. Then I had built this custom middleware which would hide and show the iframe when navigating too and from the Legacy SPA App to the React App. At first, this was a neat solution. It looked great and worked well.

When I presented my solution to my colleagues, they were happy with the outcome. However, they challenged me to simplify the architecture and use Redux Architecture with Redux-Saga as middleware and making use of Redux-Saga side effects for rendering components onto the DOM. This would get rid of the iframe and simplify the middleware to dispatch actions to redux and sagas and make use of Backbone events. This way any new developer joining the project would not need to learn my custom middleware but use existing tech knowledge they know about Redux and Backbone.

The Final Architecture
I cannot post the actual code as that is company property. However, the beauty of these patterns I used during the prototype phase are so simple and straightforward that I have recreated them for this blog post.

Hybrid app solution detail view
Hybrid app solution detail view

React App

  • Redux
  • React-Redux
  • Redux-Sagas

Legacy SPA App

  • jQuery
  • Some JavaScript Library
  • React-Middleware – used for dispatching actions

So the Legacy SPA does not have a clue about React it just continues to run as it does currently. We have a React-middleware which dispatches actions from the Legacy SPA to Redux or Sagas.

Storing User Info in Redux
So example currently on our SPA when a User logs in, after login, the react-middleware dispatches an action with User login payload, this is sent to Redux and the User data is stored in our Redux store for use for by our React App.

Rendering/Mount React Component
This is probably one of the coolest things I learnt about React which is the possibility of rendering multiple components onto the DOM. Now I didn’t know React could do this. However, I recently learnt from a conference talk that this is how they use React at Facebook.

In our SPA we decided to use redux-sagas side-effects to also render components onto the DOM for us. Therefore, on the Legacy SPA, an action is dispatched with a DOM element ID. Then a saga listening to this action uses that element ID to render a component onto that DOM element using ReactDOM.render(). The great thing about this is we are respecting the Redux Architecture, by simple dispatching an action, this easy to understand even for new people joining our team.

Rendering/mount react component using sagas side effects pattern
Rendering/mount react component using sagas side effects pattern

Un-Rendering/Dismount React Component

un-rendering/dismount react component using sagas side effects pattern
un-rendering/dismount react component using sagas side effects pattern

Where are we now
We have just finished our first feature in React, and it is working great inside the Legacy SPA. We are about to start creating more new features using React rapidly. We will also start looking at converting existing functionality over to React. The remarkable thing about this Hybrid solution, is we are keeping business happy by delivering the features they want. We as developers have created a great developer experience for ourselves.