How to Manage Complex Reactive forms in Angular


We've all had to manage complex forms in our Angular apps, and it can get messy really quickly. Making sure to use all that Angular has to offer for reactive forms helps make the experience better. This can be done by using nested FormGroups and FormArrays. In this article, we'll take a look at how this can help us manage a complex form.

What's the Problem?

I work at a health insurance company for my full time job. As you can imagine, we deal with a lot of forms, and some of them are very complex. For example, one form allows an employer to add an employee and their dependents to an insurance policy. The employee form alone has about 20 fields that need to be filled out, and then each dependent has 8 required fields and an optional set of address fields. There is no limit to the number of dependents that can be added to the form. The logic in the front end began to quickly grow out of control, with us manually checking to see if the form data was valid (instead of using the FormGroup.valid attribute) and making sure that the reusable forms were emitting the data to the parent component to be saved. The complexity caused us to hesitate any time we needed to edit the page. Finally I decided it was time to take another look at the page and simplify it and leverage the power of Angular and what it gives us for free.

The Form Setup

I've been working on a form at work that allows an employer to add an employee and their dependents to their health plan. The form can get complicated, since there can be multiple dependents. We were reusing the (reactive) dependent form for each dependent that was added, but were manually determining if the required fields were filled out. Each time the valuesChanged observable emitted a new value, we'd determine the validity of the form. We were doing something similar with the employee form. In addition, we also were manually taking the value of the form and emitting that to the parent container so it could be submitted when necessary.

All this was really complicated, so I did a little refactoring. The layout was similar: there was a container component for the page, an employee form component, and 0 or more dependent forms. But instead of the container component storing the value of each form after responding to a new Output emission, the children components now emit their form to the container component when the form is initialized and stored in a different form there. I know, this is confusing, but this visualization should help:

// container.component.ts

export class ContainerComponent {
    public form: FormGroup;

    constructor(private _fb: FormBuilder) {}

    ngOnInit() {
        this.form ={
            employeeForm: null,
            dependents: this._fb.array([])

    get dependentSubForms () {
        return this.form.get('dependents') as FormArray;

    employeeFormReady(form: FormGroup) {
        this.form.setControl('employeeForm', form);

    dependentSubFormReady(form: FormGroup) {

In this container component, we create the main form. This is how we'll manage the data from the employee form and all the dependents. When a form is initialized, we'll add it to the main form object. In the case of the employee form, we set the employeeForm control to a FormGroup, which is contained in a child component. The dependent forms are managed essentially the same way, but they are added to a FormArray instead of a single control.

At this point, the form in ContainerComponent will get all updated values from the children components, as well as set its validity based on the forms coming from the children components. When we're ready to get the value from all the forms, the form object in the ContainerComponent will contain all the data entered.

You can play with a demo here on StackBlitz.


This may seem a little complicated, but it is easier than the alternative method that we were managing previously. Angular is really powerful, and there's no need for us to do its job for it. This manner is also flexible. It can be used in the way I did above, but I also used the same format recently to build a multi step form. Each time a new portion of the form was shown on the page, we added a new control to the form. It made managing each step really easy.

This is also not the only way to do this. One way that was suggested was using ControlValueAccessors, and that is another way that I'll look into in the future to see how it compares to what we're now doing.

Original article source at:

#angular #reactive 

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Angular 11 Reactive Forms Validation Tutorial

Reactive form validation in Angular 11 app. In this tutorial, i will show you how to use reactive form validation in angular 11 app.

As well as, and you will learn how use reactive form validation in angular 11. And also use reactive form with formGroup for validation in angular 11 app.

Reactive Form Validation In Angular 11
Step 1 – Create New Angular App
Step 2 – Import Form Module
Step 3 – Add Code on View File
Step 4 – Use Component ts File
Step 5 – Start Angular App

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Roberta  Ward

Roberta Ward


Wondering how to upgrade your skills in the pandemic? Here's a simple way you can do it.

Corona Virus Pandemic has brought the world to a standstill.

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Since most of the places are on lockdown, and you are working from home or have enough time to nourish your skills, then you should use this time wisely! We always complain that we want some ‘time’ to learn and upgrade our knowledge but don’t get it due to our ‘busy schedules’. So, now is the time to make a ‘list of skills’ and learn and upgrade your skills at home!

And for the technology-loving people like us, Knoldus Techhub has already helped us a lot in doing it in a short span of time!

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Christa  Stehr

Christa Stehr


Install Angular - Angular Environment Setup Process

Angular is a TypeScript based framework that works in synchronization with HTML, CSS, and JavaScript. To work with angular, domain knowledge of these 3 is required.

  1. Installing Node.js and npm
  2. Installing Angular CLI
  3. Creating workspace
  4. Deploying your First App

In this article, you will get to know about the Angular Environment setup process. After reading this article, you will be able to install, setup, create, and launch your own application in Angular. So let’s start!!!

Angular environment setup

Install Angular in Easy Steps

For Installing Angular on your Machine, there are 2 prerequisites:

  • Node.js
  • npm Package Manager

First you need to have Node.js installed as Angular require current, active LTS or maintenance LTS version of Node.js

Download and Install Node.js version suitable for your machine’s operating system.

Npm Package Manager

Angular, Angular CLI and Angular applications are dependent on npm packages. By installing Node.js, you have automatically installed the npm Package manager which will be the base for installing angular in your system. To check the presence of npm client and Angular version check of npm client, run this command:

  1. npm -v

Installing Angular CLI

  • Open Terminal/Command Prompt
  • To install Angular CLI, run the below command:
  1. npm install -g @angular/cli

installing angular CLI

· After executing the command, Angular CLI will get installed within some time. You can check it using the following command

  1. ng --version

Workspace Creation

Now as your Angular CLI is installed, you need to create a workspace to work upon your application. Methods for it are:

  • Using CLI
  • Using Visual Studio Code
1. Using CLI

To create a workspace:

  • Navigate to the desired directory where you want to create your workspace using cd command in the Terminal/Command prompt
  • Then in the directory write this command on your terminal and provide the name of the app which you want to create. In my case I have mentioned DataFlair:
  1. Ng new YourAppName

create angular workspace

  • After running this command, it will prompt you to select from various options about the CSS and other functionalities.

angular CSS options

  • To leave everything to default, simply press the Enter or the Return key.

angular setup

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Clara  Gutmann

Clara Gutmann


Angular 8 Forms | Angular Reactive and Template Forms

Angular Forms are used to handle the user’s input. We can use Angular form in our application to enable users to log in, update profiles, enter information, and to perform many other data-entry tasks.

If you are new to Angular, then check out myAngular Tutorial. If you do not know how to upgrade to Angular 8 via Angular CLI, then check out my Angular Upgrade tutorial. Managing user input with forms is the cornerstone of many web applications.

The web app uses forms to enable the users to log in, to update a profile, to enter sensitive information, and to perform many data-entry tasks.

#angular #angular 8 #angular reactive

Angular Form Generator & Pitfalls

Ever felt repetitive creating forms in your Angular Application? Let’s fix it.


During the Front-end development days it feels like there is a lot of repetitive code which I have to write to design my forms which are almost all the time very close one to another.

I’ve been recently looking into ways of automating it. The furthest I wanted to go was to have some kind of interface between a more friendly modelling object as well as to an interface to link my objects to the Angular Modelling Universe.

This way, I discovered there is already a library that could do it for me formly. But looking over their documentation I realized this is a little bit more than I wanted.

As a result, I ended writing my own form generator. You’ll see that except for two or three pitfalls this is rather easy to achieve.


I’ll be using Angular Materials to generate my forms.

I have two tips to share about their design. It can be difficult to change the colors or design a theme for them. You’ll see the documentation on their side is rather not the best on this subject. My piece of advice, use In case you don’t know exactly what colors to use but you have a slight idea about it, I recommend using In the end you’ll definitely discover some very cool Angular Material Theme which you can even share with others.

Getting Started

First of all, we’ll organize our application on modules. When it comes to Angular I always split the code in presentation and business. From where I’m standing, presentation means those components that deal with UX functionality, they can work by themselves but they don’t make sense for a user taken alone; business are those components that configure and group together presentation through a context.

#angular-forms #angular #typescript #angular-formly