Table of Content

Riverty Components in Angular Forms

Handling data binding and validation between a web-component and Angular forms involves establishing a communication bridge between the two, as they have different ways of handling form data and validation. Here are some general steps to handle data binding and validation between the two:

  1. Two-Way Data Binding: To enable data binding between your Angular form and the web component, you should establish a two-way data binding mechanism. This typically involves using Angular’s property binding and event binding.

    For example, if your web component has a property called value and you want to bind it to an Angular form control, you can use property binding to set the initial value and event binding to update the form control when the web component’s value changes:


    In the Angular component, you would have the corresponding functions:

    formControlValue: any; // Initialize this with the initial value from the form control
    updateFormControl(newValue: any) {
      this.formControlValue = newValue;
      // Update your Angular form control here
  2. Custom Validators: If your web component has custom validation rules, you can create custom validators in Angular to handle these rules. Angular allows you to create custom validators by implementing the ValidatorFn interface.

    For example, if you want to validate a form control based on a custom condition from the web component:

    import { AbstractControl, ValidationErrors, ValidatorFn } from '@angular/forms';
    function customValidator(webComponentValue: any): ValidatorFn {
      return (control: AbstractControl): ValidationErrors | null => {
        if (webComponentValue === control.value) {
          return null; // Validation passes
        } else {
          return { customError: true }; // Validation fails

    You can then use this custom validator with your form control.

  3. Subscribing to Form Control Changes: To handle changes in the Angular form controls and update the web component’s value accordingly, you can subscribe to changes in the form control.

    formControl.valueChanges.subscribe(newValue => {
      // Update the web component's value here
  4. Handling Events: If the web component emits events related to changes in its value, you can subscribe to those events in your Angular component. When the web component emits an event, update the corresponding Angular form control.

    For example, if your web component emits a valueChange event:

    // In the Angular component
    rInput.valueChange.subscribe(newValue => {
      // Update your form control with the new value
  5. Error Messages and Display: To handle validation error messages and display them to the user, you can use Angular’s built-in error handling mechanisms, such as the ngIf directive to conditionally display error messages based on the form control’s validation status.

  6. Communication and API Documentation: Consult the documentation for your web component to understand its API, events, and properties to ensure proper integration with Angular forms.

Remember that the exact implementation details will depend on the specific web component you are using and the validation requirements of your form. Custom data binding and validation logic may be necessary based on the behavior of the web component.