Angular Reactive Forms Add Form Control And Remove Form Control Dynamically (Learn it in 15 Steps)

Srikanth
11 min readOct 24, 2022

Hi Everyone !!!, Thanks for visiting my medium I hope you doing well “Wish you a very Happy Diwali 2022”. Please find the below steps to implement the Reactive Forms and Also how to add and remove form controls in the angular application dynamically.

Photo by Justin Morgan on Unsplash

0. Before starting the application, you need to know about Reactive Forms in angular. If you know about forms you can ignore this step.

Basically, We are using forms for taking the inputs from the user and storing those inputs inside the database, In that way, we can store the information permanently. For taking the inputs from the user we need to create a form at the UI level.

We have a two-way data binding concept in side form syntax to save the details in angular .ts file and sent it back to the server by using ajax calls, But it is not a good way. So in angular, we have two approaches to implement forms and form validations.

Those are two approaches inside reactive forms,

  • Template Driven Forms
  • Reactive Forms

But in the Template-driven forms approach, we will write most of the code in Html. But in this approach, if you want to do any implementations most of them we will write inside an Html file(validations etc.).

And in the Reactive Forms approach, we will write the logic at .ts file ( Creating form groups, form controls, and validations, etc. )and it is an industry-level approach (Meaning most of the industries will follow this approach only).

In Reactive Forms, by using Form builder we can create forms and In Form Builder, we have form groups, form controls, and form arrays. By combining form groups, Form arrays and form controls we will create the forms ( Here form controls are like input fields ).

I think you understood something, In the below example, I am going to implement remove form control and add form control based on selection change inside forms. For more information, please visit the official angular.io website.

  1. Create an angular project with the below command.
ng new angular-forms-add-or-remove-control

2. After successful creation of the angular app, change the file directory to project-name. by using the below command

cd angular-forms-add-or-remove-control

3. Open the project in vs code using “code .” or open with “vs code” after that run the project by using the “ng serve” command and Open the project in chrome using localhost:4200

4. Open the app component in vs code and remove the content which is created by angular CLI while creating the app.

If you know how to add bootstrap in the angular application, You can ignore the below step (Step No 5).

5. Install the bootstrap library by using the below command and also import the URL inside styles.scss file to load the bootstrap styles inside the application.

npm install bootstrap
  • Import the bootstrap in styles.scss file as below
@import ‘../node_modules/bootstrap/dist/css/bootstrap.min.css’;

6. Open the “app.module.ts” file in vs code by using Ctrl + P and add “ReactiveFormsModule”, and “FormsModule” in imports[].

import { FormsModule, ReactiveFormsModule } from '@angular/forms';
@NgModule({
declarations: [
AppComponent,
SignupComponent
],
imports: [
BrowserModule,
AppRoutingModule,
ReactiveFormsModule,
FormsModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }

7. Open the “app.component.ts” file in vs code by using Ctrl + P and add “FormBuilder” as a dependency in “constructor”.

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup} from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder: FormBuilder){}
public ngOnInit(): void {}

}

8. Create a form variable above the constructor and formInit() method to initialize the form and call the formInit() method from either constructor or ngOnInit.

import { Component, OnInit } from '@angular/core';
import { FormBuilder,FormGroup} from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder: FormBuilder){
this.formInit();
}
public ngOnInit(): void {}public formInit(){}

}

9. And create a formGroup using formBuilder and add the form controls e.g. firstName, secondName, etc. inside the form group in the following way.

import { Component, OnInit } from '@angular/core';
import { FormBuilder, Validators, FormGroup} from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder: FormBuilder){
this.formInit()
}
public ngOnInit(): void {}public formInit(){
this.form = this.formBuilder.group({
firstName:['', Validators.required],
secondName:['', Validators.required],
middleName:[''],
username:['', Validators.required],
email:['', Validators.required],
mobile:['', [Validators.required,Validators.minLength(10),Validators.maxLength(10)]],
password:['', Validators.required],
workStatus:['', Validators.required],
gender:['', Validators.required],
qualifications:[[]],
})

}

}

10. Oops !! Not added Html inside app.component.html file to display the form in the UI. Add the form tag inside app.component.html and also add the formGroup value as a form tag attribute.

<div class="container-fluid mt-3">
<form class="form" [formGroup]="form">
<h3 class="mt-3 mb-3">User Registration</h3>
</form>
</div>

11.After that add, the input tag along with formControlName is “firstName”

<div class="container-fluid mt-3">
<form class="form" [formGroup]="form">
<h3 class="mt-3 mb-3">User Registration</h3>
<fieldset>
<legend>
User Details
</legend>
<div class="row mt-3">
<label class="label col-md-2" for="firstName">First Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="firstName" name="firstName"
id="firstName" placeholder="Enter First Name" />
</div>

</fieldset>
</form>
</div>

12. Same way add all the formControls in the following way along with radio and select dropdowns. Also, display form values inside the Html file to check the values when we changed the content inside the input.

<div class="container-fluid mt-3">
<form class="form" [formGroup]="form">
<h3 class="mt-3 mb-3">User Registration</h3>
<fieldset>
<legend>
User Details
</legend>
<div class="row mt-3">
<label class="label col-md-2" for="firstName">First Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="firstName" name="firstName"
id="firstName" placeholder="Enter First Name" />
</div>

<div class="row mt-2">
<label class="label col-md-2" for="secondName">Second Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="secondName" name="secondName"
id="secondName" placeholder="Enter Second Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="middleName">Middle Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="middleName" name="middleName"
id="middleName" placeholder="Enter Middle Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2">Gender</label>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="male" value="male" />
<label class="label" for="male">Male</label>
</div>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="female"
value="female" />
<label class="label" for="female">Female</label>
</div>
</div>
<div class="row mt-2">
<label class="label col-md-2" for="username">Username</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="username" name="username"
id="username" placeholder="Enter Username" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="email">Email Address</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="email" name="email" id="email"
placeholder="Enter Email Address" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="password">Password</label>
<input type="password" class="form-control form-control-sm col-md-6" formControlName="password" name="password"
id="password" placeholder="Enter Password" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="mobile">Mobile</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="mobile" name="mobile"
id="mobile" placeholder="Enter Mobile" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="workStatus">Work Status</label>
<select class="form-control form-control-sm col-md-6" formControlName="workStatus" name="workStatus"
id="workStatus">
<option value="" selected disabled>Selected</option>
<option value="Fresher">Fresher</option>
<option value="Experienced">Experienced</option>
</select>
</div>

</fieldset>
</form>
{{form.value | json }}
</div>

13. After that add, the buttons submit and reset. Here submit button is used for submitting the form and the reset button is used for resetting the values inside the form.

<div class="container-fluid mt-3">,
<form class="form" [formGroup]="form">
<h3 class="mt-3 mb-3">User Registration</h3>
<fieldset>
<legend>
User Details
</legend>
<div class="row mt-3">
<label class="label col-md-2" for="firstName">First Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="firstName" name="firstName"
id="firstName" placeholder="Enter First Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="secondName">Second Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="secondName" name="secondName"
id="secondName" placeholder="Enter Second Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="middleName">Middle Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="middleName" name="middleName"
id="middleName" placeholder="Enter Middle Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2">Gender</label>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="male" value="male" />
<label class="label" for="male">Male</label>
</div>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="female"
value="female" />
<label class="label" for="female">Female</label>
</div>
</div>
<div class="row mt-2">
<label class="label col-md-2" for="username">Username</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="username" name="username"
id="username" placeholder="Enter Username" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="email">Email Address</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="email" name="email" id="email"
placeholder="Enter Email Address" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="password">Password</label>
<input type="password" class="form-control form-control-sm col-md-6" formControlName="password" name="password"
id="password" placeholder="Enter Password" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="mobile">Mobile</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="mobile" name="mobile"
id="mobile" placeholder="Enter Mobile" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="workStatus">Work Status</label>
<select class="form-control form-control-sm col-md-6" formControlName="workStatus" name="workStatus"
id="workStatus">
<option value="" selected disabled>Selected</option>
<option value="Fresher">Fresher</option>
<option value="Experienced">Experienced</option>
</select>
</div>
</fieldset>
<div class="row mt-2">
<button class="btn btn-primary m-3" type="submit" [disabled]="!form.valid">Submit</button>
<button class="btn btn-danger m-3" type="button" (click)="resetForm()">Reset</button>
</div>

</form>
{{form.value | json }}
</div>

14. Check the changes inside the browser by using localhost:4200, If anything is wrong please check from the first step.

15. After that we need to add the value changes event for the “workStatus” inside ngOnInit() to get the value whenever the “workStatus” select dropdown changes. Also, create method selectionChange(value) and call the method from the valueChanges event.

import { Component, OnInit } from '@angular/core';
import { FormBuilder,Validators,FormGroup, FormControl } from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder:FormBuilder){
this.formInit()
}
public ngOnInit(): void {
this.form.get('workStatus').valueChanges.subscribe(value=>{
this.selectionChange(value);
})

}
public formInit(){
this.form = this.formBuilder.group({
firstName:['', Validators.required],
secondName:['', Validators.required],
middleName:[''],
username:['', Validators.required],
email:['', Validators.required],
mobile:['', [Validators.required,Validators.minLength(10),Validators.maxLength(10)]],
password:['', Validators.required],
workStatus:['', Validators.required],
gender:['', Validators.required],
qualifications:[[]],
})
}
public resetForm(){
this.form.reset()
}

public selectionChange(value) {

}


}

16. Up to here clear right, Next we need to add the logic for displaying the additional formControls based on the user selects the “workStatus” dropdown. If the user selected “Experienced” as the “workStatus” dropdown value then I will add the formControls else I will remove the formControls.

These are the below form controls am adding and removing on condition based

Form Controls :

“workExperience”, “currentCompany”, “currentCtc”, “expectedCtc”, “notice Period”, “skills”.

import { Component, OnInit } from '@angular/core';
import { FormBuilder,Validators,FormGroup, FormControl } from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder:FormBuilder){
this.formInit()
}
public ngOnInit(): void {
this.form.get('workStatus').valueChanges.subscribe(value=>{
this.selectionChange(value);
})
}
public formInit(){
this.form = this.formBuilder.group({
firstName:['', Validators.required],
secondName:['', Validators.required],
middleName:[''],
username:['', Validators.required],
email:['', Validators.required],
mobile:['', [Validators.required,Validators.minLength(10),Validators.maxLength(10)]],
password:['', Validators.required],
workStatus:['', Validators.required],
gender:['', Validators.required],
qualifications:[[]],
})
}
public resetForm(){
this.form.reset()
}

public selectionChange(value) {
if(value && value === 'Experienced'){
this.form.addControl('workExperience',new FormControl('',[Validators.required]));
this.form.addControl('currentCompany',new FormControl('',[Validators.required]));
this.form.addControl('currentCtc',new FormControl('',[Validators.required]));
this.form.addControl('expectedCtc',new FormControl('',[Validators.required]));
this.form.addControl('noticePeriod',new FormControl('',[Validators.required]));
this.form.addControl('skills',new FormControl('',[Validators.required]));
}else{
this.form.removeControl('workExperience');
this.form.removeControl('currentCompany');
this.form.removeControl('currentCtc');
this.form.removeControl('expectedCtc');
this.form.removeControl('noticePeriod');
this.form.removeControl('skills');
}
}

}

17. Here we need a variable for showing the data and hiding the data based on dropdown selection. I created a get method isExperienced to get the latest value as true or false. If the workStatus dropdown value is “Experienced” then will get the value as true else false.

import { Component, OnInit } from '@angular/core';
import { FormBuilder,Validators,FormGroup, FormControl } from "@angular/forms";
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
public form:FormGroup;
constructor(private formBuilder:FormBuilder){
this.formInit()
}
public ngOnInit(): void {
this.form.get('workStatus').valueChanges.subscribe(value=>{
this.selectionChange(value);
})
}
public formInit(){
this.form = this.formBuilder.group({
firstName:['', Validators.required],
secondName:['', Validators.required],
middleName:[''],
username:['', Validators.required],
email:['', Validators.required],
mobile:['', [Validators.required,Validators.minLength(10),Validators.maxLength(10)]],
password:['', Validators.required],
workStatus:['', Validators.required],
gender:['', Validators.required],
qualifications:[[]],
})
}
public resetForm(){
this.form.reset()
}
public get isExperienced(){
const value = this.form.get('workStatus').value;
return value && value === 'Experienced';
}


public selectionChange(value) {
if(value && value === 'Experienced'){
this.form.addControl('workExperience',new FormControl('',[Validators.required]));
this.form.addControl('currentCompany',new FormControl('',[Validators.required]));
this.form.addControl('currentCtc',new FormControl('',[Validators.required]));
this.form.addControl('expectedCtc',new FormControl('',[Validators.required]));
this.form.addControl('noticePeriod',new FormControl('',[Validators.required]));
this.form.addControl('skills',new FormControl('',[Validators.required]));
}else{
this.form.removeControl('workExperience');
this.form.removeControl('currentCompany');
this.form.removeControl('currentCtc');
this.form.removeControl('expectedCtc');
this.form.removeControl('noticePeriod');
this.form.removeControl('skills');
}
}

}

18. After that, open app.component.html, and add the below code and condition for showing the data based on the workStatus dropdown selection.

<div class="container-fluid mt-3">
<form class="form" [formGroup]="form">
<h3 class="mt-3 mb-3">User Registration</h3>
<fieldset>
<legend>
User Details
</legend>
<div class="row mt-3">
<label class="label col-md-2" for="firstName">First Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="firstName" name="firstName"
id="firstName" placeholder="Enter First Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="secondName">Second Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="secondName" name="secondName"
id="secondName" placeholder="Enter Second Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="middleName">Middle Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="middleName" name="middleName"
id="middleName" placeholder="Enter Middle Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2">Gender</label>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="male" value="male" />
<label class="label" for="male">Male</label>
</div>
<div class="col-md-1">
<input type="radio" class="form-check-input" formControlName="gender" name="gender" id="female"
value="female" />
<label class="label" for="female">Female</label>
</div>
</div>
<div class="row mt-2">
<label class="label col-md-2" for="username">Username</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="username" name="username"
id="username" placeholder="Enter Username" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="email">Email Address</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="email" name="email" id="email"
placeholder="Enter Email Address" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="password">Password</label>
<input type="password" class="form-control form-control-sm col-md-6" formControlName="password" name="password"
id="password" placeholder="Enter Password" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="mobile">Mobile</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="mobile" name="mobile"
id="mobile" placeholder="Enter Mobile" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="workStatus">Work Status</label>
<select class="form-control form-control-sm col-md-6" formControlName="workStatus" name="workStatus"
id="workStatus">
<option value="" selected disabled>Selected</option>
<option value="Fresher">Fresher</option>
<option value="Experienced">Experienced</option>
</select>
</div>
</fieldset>
<ng-container *ngIf="isExperienced">
<fieldset>
<legend>
Work Experience
</legend>
<div class="row mt-2">
<label class="label col-md-2" for="workExperience">Total Years of Experience</label>
<select class="form-control form-control-sm col-md-6" formControlName="workExperience" name="workExperience"
id="workExperience">
<option value="" selected disabled>Select Years Of Experience</option>
<option value="0-1">0 to 1 Year</option>
<option value="1-2">1 to 2 Years</option>
<option value="3-5">3 to 5 Years</option>
<option value="5-7">5 to 7 Years</option>
<option value="7-10">7 to 10 Years</option>
<option value="10-or-more">More than 10 Years</option>
</select>
</div>
<div class="row mt-2">
<label class="label col-md-2" for="currentCompany">Current Company Name</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="currentCompany"
name="currentCompany" id="currentCompany" placeholder="Enter Current Company Name" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="currentCtc">Current CTC</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="currentCtc"
name="currentCtc" id="currentCtc" placeholder="Enter Current CTC" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="expectedCtc">Expected CTC</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="expectedCtc"
name="expectedCtc" id="expectedCtc" placeholder="Enter Expected CTC" />
</div>
<div class="row mt-2">
<label class="label col-md-2" for="skills">Skills Set</label>
<input type="text" class="form-control form-control-sm col-md-6" formControlName="skills" name="skills"
id="skills" placeholder="Enter Skills E.g. Java,Python" />
</div>
<div class="row mt-2">
<p class="m-3" style="color: red;">Note:: Give Skills as comma separated e.g. java,python</p>
</div>
<div class="row mt-2">
<label class="label col-md-2" for="noticePeriod">Notice Period</label>
<select class="form-control form-control-sm col-md-6" formControlName="noticePeriod" name="noticePeriod"
id="noticePeriod">
<option value="" selected disabled>Select Notice Period</option>
<option value="immediate-joiner">Immediate Joiner</option>
<option value="15-or-less-than">15 days or less than</option>
<option value="1-month">1 Month</option>
<option value="45-days">45 Days</option>
<option value="2-months">2 Months</option>
<option value="3-months">3 Months</option>
<option value="more-than-3months">More than 3 months</option>
</select>
</div>
</fieldset>
</ng-container>

<div class="row mt-2">
<button class="btn btn-primary m-3" type="submit" [disabled]="!form.valid">Submit</button>
<button class="btn btn-danger m-3" type="button" (click)="resetForm()">Reset</button>
</div>
</form>
{{form.value | json }}
</div>

19. Finally Added all the code, Please test the changes inside the browser, and If anything is wrong please check carefully from the first step.

Output:

SOURCE CODE:
Front End:
GitHub: https://github.com/mryenagandula/angular-forms-add-or-remove-control

Stack blitz Project Preview:
https://stackblitz.com/edit/angular-forms-add-control-remove-control

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Srikanth

Senior Software Engineer | Storyteller | Quick Learner | React JS | Angular | Java | Learn Something new from my stories