Many front-end apps, particularly those used for enterprise development, are heavily form-driven. Many of these applications are really just large forms that span several tabs and dialogue boxes and include complex business logic for validation. Here we discuss what are the practical difference between reactive forms & template driven forms.
Ng Model Two Way Binding in Template Driven Form
The simplest way to create a form in Angular is through a template-driven approach. In order to construct and manage the underlying form object, it makes use of Angular's two-way data-binding directive (ngModel).
Using two-way binding, it is feasible to display a data property and update it in response to user input. The two-way binding enables data interaction between components of your app in both directions. You will be able to listen to events and update data between parent and child components at the same time. Two-way data binding is nothing more than the application of both property binding and event binding. A route from a component to a view is through property binding. One route from the view to the component is through the event binding. Both can be combined to create a two-way binding.
Reactive Form
On the surface, a reactive form resembles a template-driven form quite a bit. Reactive forms are built using "ReactiveFormsModule" while template-driven forms use the "FormsModule" Reactive forms are primarily synchronous, whereas template-driven forms are asynchronous in nature. The domain model is used to bind FormControl objects to form control elements provided by Angular ngModel. The ngModel directive can be used to link an HTML control to an application (such as an input, select, or textarea).
Forms typically contain several related controls. There are two methods for combining various related controls into a single input form using reactive forms. They are form group and form array. Every form in Angular Reactive Forms has a form model that is defined programmatically using either the FormControl and FormGroup APIs or the shorter FormBuilder API.
The group name directive on the < div> allows us to access nested form controls like fromControlName="street" that are children of that element directlyinstead of writing "street.address" when the address sub-form is implemented inline.
Form Group describes a form having a certain number of controls that you can control collectively. The basics of form groups are covered in this section. To develop more complicated forms, form groups can also be nested and a Form array defines a dynamic form that allows for run-time addition and removal of controls. Form arrays can also be nested to produce more complicated shapes. See Creating dynamic forms for additional information on this choice.
Reactive Forms Validation
Form validation is a crucial step that adds a security layer to prevent unauthorized individuals from abusing web forms. Checking that the data is in the correct format before sending it to the server is crucial. This Angular forms validation example demonstrates how to correctly validate a form and secure your Angular Application. Reactive forms provide a model-driven method of handling form inputs with often changing values.
Example:
HTML
this.userForm = this.formBuilder.group({
firstName: ['', [Validators.required, Validators.pattern('^[a-zA-Z]+$')]],
lastName: ['',[Validators.required, Validators.pattern('^[a-zA-Z]+$')]],
email: ['', [Validators.required, Validators.email]]
});
< div class="col custom-col">
< input type="text" formControlName="firstName" id="defaultRegisterFormFirstName"
class="form-control" placeholder="First name">
< span>* First Name is required< /span>
< /div>
TypeScript
this.userForm = this.formBuilder.group ({
firstName: ['', [Validators.required, Validators.pattern('^[a-zA-Z]+$')]],
lastName: ['',[Validators.required, Validators.pattern('^[a-zA-Z]+$')]],
email: ['', [Validators.required, Validators.email]]
});
There are Some Types of Validation
- Inbuilt Validation in Angular
- Custom Validation
Example:
HTML
< div class="custom-col">
< input type="email" formControlName="email" id="defaultRegisterFormEmail"
class="form-control mb-4" placeholder="E-mail">
< span *ngIf="formSubmitted && userForm.get('email').hasError('duplicateEmailId')">
* Email Id already exists !!
< /span>
< /div>
TypeScript
duplicateEmailValidator(control: FormControl){
let email = control.value;
if (email && this.emailIds.includes(email)) {
return {
duplicateEmailId: { email: email }
}
}
return null;
}
Reactive forms and template-driven forms are the two most existing features of form methods in angular. Reactive forms are easier to interact with and also easy for error handling. It helps the developers to build pretty good forms. Now you Can Implement As Many Ractive & Template driven forms In Your Project As Possible.
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