CUSTOMER FEEDBACK FORM WITH REACTIVE FORMS IN ANGULAR (BG WEB AGENCY)

1. Intro - Model Driven Forms or Reactive Forms

Reactive forms helps us manage the state of a form at a given point in time. It helps us to write some executable code when any value or state changes. It helps us to write complex validation rules in code. It has direct access to the data model of our form. The logic which we implement in model driven forms can be tested. And thus unit test can be done. Reactive forms are used to implement more advance forms. Template driven forms are mainly for simpler implementations.

ng new feedback-form

2. Create a Form Component

create a component: ng g c feedback-form

3. ReactiveFormsModule && FormGroup

app.module.ts file import ReactiveFormsModule import { ReactiveFormsModule } from '@angular/forms';

feedback-form.component.ts import { FormGroup } from '@angular/forms'; Form group represents the entire form that we are going to build.

FormBuilder is used to build the form. import { FormGroup } from '@angular/forms';

4. HTML and CSS

styles.css, feedback-form.component and app.component

5. Creating FormControl

FormGroup represents the entire form. And the individual form elements will be represented by FormControl. Thus, FormControl is the building block of a FormGroup. import { FormGroup, FormBuilder, FormControl } from '@angular/forms';

6. Creating nested form groups

Creating form groups inside form groups for holding similar form control elements e.g a group of checkboxes

7. Creating Form Controls inside nested form groups

8. Creating Form Controls for radio buttons

Radio buttons is just a single input. Thus we are not having a different form group for this. While checkbox has multiple inputs with multiple values, so having a form group to wrap them around.

9. Creating Form Array for dynamic elements

A Form Array is also like Form Group and can be used to create multiple form control elements. This is unique in the way that we can create/add/delete form control elements inside it.

10. Creating Add/Delete functions

11. Pre filling data in form

In HTML we use "value" attribute. Thus giving the same data from value of an input into form control will set it as default selection.

12. Pre filling data in form with setValue in ngOnInit

13. reset()

Any form group or form control or form array can be cleared with reset()

14. Showing form data on HTML

json pipe used to view HTML data for easier coding

15. Submit Feedback Form

(ngSubmit)

WIRING FORMGROUP FROM TS INTO HTML

16. formControlName

It links formcontrol created in ts with input file in html. This also takes care of two way binding of input.

17. formArrayName and looping through form array controls

Adding/removing more feedbacks

18. formGroupName and formControlName for nested form groups in checkboxes

19. Adding formControlName to select

We can use [ngValue] from [ngSelect] to save object in a select also instead of just a string. Thus makes coding easier.

20. Adding formControlName to textarea

21. Adding formControlName to radio buttons

Note that better to replace name with formControlName or. Name and formControlName should be same.

22. Hiding the detailed feedback section if gender is male

Use get handler to get any formcontrol value in HTML template

23. Change classes

ng-untouched - if input has not been touched even once ng-touched - if input is once touched or focused ng-pristine - if input's value has not been changed even once ng-dirty - if input's value has changed atleast once

24. Using valueChanges event to subscribe to change event of an input

valueChanges.subscribe and .get() handler

25. Using Validators

26. Validators.required with error message

27. Array of validations

Validators.required, Validators.minLength to get errors data: use the errors property from the formscontrol object

28. Complex/Custom Validators

Show error message if customer has a Washing Machine product and tries to choose Proper Installation option

29. Disabling submit button if form is not valid

30. Build and move to server

ng build change base href="/projects/ui/customer-feedback-form/"