Angular use modal dialog in canDeactivate Guard service for unsubmitted changes (Form dirty)

Question

In my Angular 4 application I have some components with a form, like this:

export class MyComponent implements OnInit, FormComponent {

  form: FormGroup;

          


        

Answer 1

This is my implementation to get a confirmation dialog before leaving a certain route using ngx-bootstrap dialog box. I am having a global variable called 'canNavigate' with the help of a service. This variable will hold a Boolean value if it is true or false to see if navigation is possible. This value is initially true but if I do a change in my component I will make it false therefore 'canNavigate' will be false. If it is false I will open the dialog box and if the user discards the changes it will go to the desired route by taking the queryParams as well, else it will not route.

@Injectable()
export class AddItemsAuthenticate implements CanDeactivate {

  bsModalRef: BsModalRef;
  constructor(private router: Router,
              private dataHelper: DataHelperService,
              private modalService: BsModalService) {
  }

  canDeactivate(component: AddUniformItemComponent,
                route: ActivatedRouteSnapshot,
                state: RouterStateSnapshot,
                nextState?: RouterStateSnapshot): boolean {
    if (this.dataHelper.canNavigate === false ) {
      this.bsModalRef = this.modalService.show(ConfirmDialogComponent);
      this.bsModalRef.content.title = 'Discard Changes';
      this.bsModalRef.content.description = `You have unsaved changes. Do you want to leave this page and discard
                                            your changes or stay on this page?`;

      this.modalService.onHidden.subscribe(
        result => {
          try {
            if (this.bsModalRef && this.bsModalRef.content.confirmation) {
              this.dataHelper.canNavigate = true;
              this.dataHelper.reset();;
              const queryParams = nextState.root.queryParams;
              this.router.navigate([nextState.url.split('?')[0]],
                {
                  queryParams
                });
            }
          }catch (exception) {
            // console.log(exception);
          }
        }, error => console.log(error));
    }

    return this.dataHelper.canNavigate;

  }
}