How to force a component s re-rendering in Angular 2

Question

How to force a component s re-rendering in Angular 2  For debug purposes working with Redux i d like to force a component to re-render it s view  is that possible

User · Answer

I force reload my component using  ngIf   All the components inside my container goes back to the full lifecycle hooks     In the template      lt ng-container  ngIf   reload  gt      components here   lt  ng-container gt    Then in the ts file    public  reload   true   private reload         setTimeout      gt  this  reload   false       setTimeout      gt  this  reload   true

User · Answer

Other answers here provide solutions for triggering change detection cycles that will update component s view  which is not same as full re-render    Full re-render  which would destroy and reinitialize component  calling all lifecycle hooks and rebuilding view  can be done by using ng-template  ng-container and ViewContainerRef in following way    lt div gt     lt ng-container  outlet  gt     lt  ng-container gt   lt  div gt    lt ng-template  content gt     lt child gt  lt  child gt   lt  ng-template gt    Then in component having reference to both  outlet and  content we can clear outlets  content and insert another instance of child component    ViewChild  outlet    read  ViewContainerRef   outletRef  ViewContainerRef   ViewChild  content    read  TemplateRef   contentRef  TemplateRef lt any gt    private rerender         this outletRef clear        this outletRef createEmbeddedView this contentRef       Additionally initial content should be inserted on AfterContentInit hook   ngAfterContentInit         this outletRef createEmbeddedView this contentRef       Full working solution can be found here https   stackblitz com edit angular-component-rerender

User · Answer

Rendering happens after change detection   To force change detection  so that component property values that have changed get propagated to the DOM  and then the browser will render those changes in the view   here are some options    ApplicationRef tick   - similar to Angular 1 s  rootScope  digest   -- i e   check the full component tree NgZone run callback  - similar to  rootScope  apply callback  -- i e   evaluate the callback function inside the Angular 2 zone  I think  but I m not sure  that this ends up checking the full component tree after executing the callback function  ChangeDetectorRef detectChanges   - similar to  scope  digest   -- i e   check only this component and its children   You will need to import and then inject ApplicationRef  NgZone  or ChangeDetectorRef into your component   For your particular scenario  I would recommend the last option if only a single component has changed

User · Answer

ChangeDetectorRef approach  import   Component  OnInit  ChangeDetectorRef   from   angular core    export class MyComponent        constructor private cdr  ChangeDetectorRef           selected item  any            if  item     Department               this isDepartment   true          else             this isDepartment   false          this cdr detectChanges

User · Answer

tx  found the workaround I needed     constructor private zone NgZone           enable to for time travel     this appStore subscribe  state    gt            this zone run      gt                console log  enabled time travel                          running zone run will force the component to re-render

User · Answer

ChangeDetectorRef detectChanges   is usually the most focused way of doing this  ApplicationRef tick   is usually too much of a sledgehammer approach   To use ChangeDetectorRef detectChanges    you ll need this at the top of your component   import    ChangeDetectorRef   from   angular core         then  usually you alias that when you inject it in your constructor like this   constructor  private cdr  ChangeDetectorRef            Then  in the appropriate place  you call it like this   this cdr detectChanges      Where you call ChangeDetectorRef detectChanges   can be highly significant  You need to completely understand the life cycle and exactly how your application is functioning and rendering its components  There s no substitute here for completely doing your homework and making sure you understand the Angular lifecycle inside out  Then  once you understand that  you can use ChangeDetectorRef detectChanges   appropriately  sometimes it s very easy to understand where you should use it  other times it can be very complex

[angular] How to force a component's re-rendering in Angular 2?

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