Enhancing template-driven forms with validation directly from a component in Angular 6

When working with Angular 6, there are two main approaches for creating forms:

  1. The Model-driven approach
  2. The Template-driven approach

In the Model-driven approach, validators are defined within the component code. On the other hand, in the Template-driven approach, validators are defined using directives and HTML5 attributes directly in the template.

Is it possible to define validation from the component code in a Template-driven form?

I have a requirement where I need to dynamically change the validation of a text box based on user input.

<input type="text" [(ngModel)]="value" (input)="ValueChangeEvent(myvalue)" />

Here, in the ValueChangeEvent method, I want to modify the validation rules of the textbox. For example, adding minimum value validation only when the user enter some input.

angulartypescriptvalidationangular6

Answer №1

Utilize ControlValueAccessor for Developing Unique Form Controls in Angular

A ControlValueAccessor serves as a connection between the Angular forms API and a specific element within the DOM.

When crafting forms in Angular, there may be instances where you require an input that deviates from the typical text input, select, or checkbox. By adhering to the ControlValueAccessor interface and enrolling the component as an NG_VALUE_ACCESSOR, you can seamlessly incorporate your distinctive form control into template-driven or reactive forms just like any standard input field!

For further information, visit:https://alligator.io/angular/custom-form-control/

Here's an example demonstrating customFormValidation:https://stackblitz.com/edit/angular-hhgkje

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