Angular 2 View will not update after variable change in subscribe

Question

are you seeing any error on console? This could be due to fact that angular is not running change detection after you have made updates to value. I think you don't need ngZone.run as it will run code outside the angular zone.

this.questionService.onSubmit(form, this.questions).subscribe( (value) => {
            this.fileLocation = JSON.stringify(value);
            console.log(this.fileLocation);
            this.isRequesting = "false";
            console.log(this.isRequesting);
    });

If due to some reason you need to run this outside Angular zone, then you should inform angular to run a change detection cycle by either of this method.

• just wrap update of isRequesting in set timeout

  setTimeout( () => this.isRequesting = "false", 0);
  

• invoking change detection manually

  import {ChangeDetectorRef} from '@angular/core'
  constructor(private ref: ChangeDetectorRef){}
  
  this.questionService.onSubmit(form, this.questions).subscribe( (value)=> {
      //existing code
      console.log(this.isRequesting);
      this.ref.detectChanges();
  });
  

You can also try this solution: Guide from Thoughtram

Short version:

 import { ChangeDetectorRef } from '@angular/core';
    ...
    constructor(private cd: ChangeDetectorRef) {}
    ...
    ... .subscribe( () => {
           <yourstuff>
           this.cd.markForCheck();
        }

and you are good.

Background: when changing a value via .subscribe() angular does not notify that it should run changedetection. So you need to run it yourself.

You can switch (on/off) template updating via changeDetection. You have to put your choice of strategy into component definition. You can choose Default or OnPush strategy.

@Component({
    selector: '...............',
    templateUrl: '.......html',
    styleUrls: ['..........scss'],
    changeDetection: ChangeDetectionStrategy.Default
})