Category: Angular

Angular – How to force reload components with router navigation

(Tested in Angular 11 project)

One trick is to “double” navigate to force components to destroy and “update” their lifecycle.

E.g.:

/// Navigates to detail view
navigateToDetail(id: string) {

  // Navigates to start page first to "destroy" detail components if on same url
  this.router.navigate(['/']).then(() => {
    // Then navigates to desired url 
    let navigationExtras: NavigationExtras = { queryParams: { 'id': id} };
    this.router.navigate(['/view'], navigationExtras);
  });

}

I also added this to app-routing.module.ts: (not sure if it makes a difference with the above code)

@NgModule({
  imports: [RouterModule.forRoot(routes, {
    onSameUrlNavigation: 'reload',
  })],
  exports: [RouterModule],
})
export class AppRoutingModule {}

 

How to force Angular to reload components when navigating to same url

Tested in Angular 11:

In module config for route module:

@NgModule({
imports: [RouterModule.forRoot(routes, {
onSameUrlNavigation: 'reload',
})],
exports: [RouterModule],
})

Set onSameUrlNavigation to ‘reload’

Whan using router.navigate() force url to update by adding a unique query parameter:

let navigationExtras: NavigationExtras = {
  queryParams: {
     refreshToken: (new Date).getTime(); //pass a dummy parameter (i.e. the time in milliseconds since 1970 or use the npm uuid library), forces reload of unique url
  },
};
this.router.navigate(['/detail'], navigationExtras);

More info:

https://github.com/angular/angular/issues/13831

https://angular.io/api/router/Router

https://angular.io/api/router/RouteReuseStrategy

Angular 10+ Strict Mode

From Angular 10 (experimental) / 11 (default on create new app) you can get strict mode. In summary it reduces the bundle size (by 75%!) and increases the maintainability by disabling you to create objects of type ‘any’ (no untyped types)…

Angular 11+ CLI creates all new workspaces and projects with strict mode enabled.

Strict mode improves maintainability and helps you catch bugs ahead of time. Additionally, strict mode applications are easier to statically analyze and can help the ng update command refactor code more safely and precisely when you are updating to future versions of Angular.

Specifically, strict mode does the following:

More info:
https://angular.io/guide/strict-mode

Angular CLI Strict Mode. In Angular, we strongly believe in… | by Minko Gechev | Angular Blog

Angular state inspector – Chrome Extension

Helps you debug Angular component state. Supports Angular 1/2+/Ivy! Angular State Inspector for Angular Supports all versions of Angular: – AngularJs – Angular 2+ – Angular Ivy – Hybrid apps (AngularJs + Angular) Extends the Chrome Developer Tools for Angular web apps. Adds new panel “State” to Elements tab, that displays the state of selected element. Prints state of selected element in console by calling “$state” variable. Depending on angular version it can show: – Component state – Directives – Context, like ngForOf or ngIf values – Event listeners If they are applicable to the current element.

Angular State Inspector also allows you to modify the values in the “State” panel (double click on value)

Source: Angular state inspector – Chrome Web Store

Angular tips debugger – Pause Your Code With Breakpoints In Chrome DevTools

You can use this in Angular development for instance.
Just place till code on a line you wish to debug (e.g. in an component.ts file):

debugger;

Chrome will pause on that breakpoint.

Source: How To Pause Your Code With Breakpoints In Chrome DevTools

Binding select element to object in Angular

Component.ts file:

Component.ts file: 

@Component({
   selector: 'myApp',
   template: 'myApp.html'
})
export class AppComponent{
    countries = [
       {id: 1, name: "United States"},
       {id: 2, name: "Australia"}
       {id: 3, name: "Canada"},
       {id: 4, name: "Brazil"},
       {id: 5, name: "England"}
     ];
    selectedValue = null; //the current selected option id
}

Template:

<h1>My Application</h1>
<select [(ngModel)]="selectedValue">
<option *ngFor="let c of countries" [ngValue]="c">{{c.name}}</option>
</select>

StackBlitz example

NOTE: you can use [ngValue]=”c” instead of [ngValue]=”c.id” where c is the complete country object.

Source: html – Binding select element to object in Angular – Stack Overflow

Angular – Reactive forms API summary

Reactive forms API summary

The following table lists the base classes and services used to create and manage reactive form controls. For complete syntax details, see the API reference documentation for the Forms package.

Classes

Class Description
AbstractControl The abstract base class for the concrete form control classes FormControl, FormGroup, and FormArray. It provides their common behaviors and properties.
FormControl Manages the value and validity status of an individual form control. It corresponds to an HTML form control such as <input> or <select>.
FormGroup Manages the value and validity state of a group of AbstractControl instances. The group’s properties include its child controls. The top-level form in your component is FormGroup.
FormArray Manages the value and validity state of a numerically indexed array of AbstractControl instances.
FormBuilder An injectable service that provides factory methods for creating control instances.

Directives

Directive Description
FormControlDirective Syncs a standalone FormControl instance to a form control element.
FormControlName Syncs FormControl in an existing FormGroup instance to a form control element by name.
FormGroupDirective Syncs an existing FormGroup instance to a DOM element.
FormGroupName Syncs a nested FormGroup instance to a DOM element.
FormArrayName Syncs a nested FormArray instance to a DOM element.

Source: Angular – Reactive forms – API Summary