How can I set an array as a property of an object using the Angular Subscribe method?

Question

How can I set an array as a property of an object using the Angular Subscribe method?

I'm attempting to retrieve array values from the en.json translation file in Angular and then bind them to an object property using the code snippet below.

Here is the TypeScript code:

  ngOnInit() {
    this.en = {
      dayNamesMin: this.translateSvc
                  .get(['calendar.day_names_min.Sun', 'calendar.day_names_min.Mon', 'calendar.day_names_min.Tue', 'calendar.day_names_min.Wed',
                    'calendar.day_names_min.Thu', 'calendar.day_names_min.Fri', 'calendar.day_names_min.Sat'])
                  .subscribe(translated => {
                    console.log(Object.keys(translated).map(key => translated[key]));
                    return Object.keys(translated).map(key => translated[key]);
                  })
    };
  };

The en.json file has the following structure:

{
    "calendar" : {
        "day_names_min": {
            "Sun": "SUN",
            "Mon": "MON",
            "Tue": "TUE",
            "Wed": "WED",
            "Thu": "THU",
            "Fri": "FRI",
            "Sat": "SAT"
        }
    }
}

I'm utilizing the ngx translator service to extract data from the en.json file, subscribe to it, and assign the value to the dayNamesMin property of the this.en object.

Although when I log the value Object.keys(translated).map(key => translated[key]); in the console, it correctly displays the array ["SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"]. Unfortunately, it doesn't seem to bind to the object's property dayNamesMin.

Any assistance would be greatly appreciated!

angular typescript subscribe ngx-translate

Answer 1

Answer №1

When working with asynchronous data using observables, it is recommended to assign values inside the subscription rather than assuming that the variable will be assigned when accessed. In this scenario, you can implement the following

ngOnInit() {
  this.translateSvc.
    .get([
      'calendar.day_names_min.Sun', 
      'calendar.day_names_min.Mon', 
      'calendar.day_names_min.Tue', 
      'calendar.day_names_min.Wed',
      'calendar.day_names_min.Thu', 
      'calendar.day_names_min.Fri', 
      'calendar.day_names_min.Sat'
    ])
    .subscribe(translated => {
      this.en = {
        dayNamesMin: Object.keys(translated).map(key => translated[key])
      };
    });
}

It's important to note that the this.en variable won't have a value until the this.translateSvc.get() observable emits. Thus, you must consider that this.en is asynchronous when accessed.

For more information on handling async data, check here.

Alternatively, if you only intend to utilize the this.en variable in the template for displaying values, you can map the output from this.translateSvc.get() using the RxJS map operator and leverage the Angular async pipe.

Controller

en$: Observable<any>;

ngOnInit() {
  this.en$ = this.translateSvc.     // <-- assign the observable
    .get([
      'calendar.day_names_min.Sun', 
      'calendar.day_names_min.Mon', 
      'calendar.day_names_min.Tue', 
      'calendar.day_names_min.Wed',
      'calendar.day_names_min.Thu', 
      'calendar.day_names_min.Fri', 
      'calendar.day_names_min.Sat'
    ])
    .pipe(       // <-- transform the response here
      map(translated => ({ dayNamesMin: Object.keys(translated).map(key => translated[key]) }))
    );
}

Template

<ng-container *ngIf="(en$ | async) as en">
  {{ en.dayNamesMin | json }}
  {{ en.dayNamesMin[0] }}
  ...
  <p *ngFor="let day of en.dayNamesMin">
    {{ day }}
  </p>
</ng-container>

Update: Use with PrimeNg calendar

As demonstrated in the second approach, use the RxJS map operator to structure it into the required object format and incorporate it as input in the HTML template.

<ng-container *ngIf="(en$ | async) as en">
  <p-calendar 
    dateFormat="dd/mm/yy" 
    [(ngModel)]="value" 
    [locale]="en">   <!-- utilize `en` from the async pipe -->
  </p-calendar>
</ng-container>

Answer 2

When working with asynchronous data using observables, it is recommended to assign values inside the subscription rather than assuming that the variable will be assigned when accessed. In this scenario, you can implement the following

ngOnInit() {
  this.translateSvc.
    .get([
      'calendar.day_names_min.Sun', 
      'calendar.day_names_min.Mon', 
      'calendar.day_names_min.Tue', 
      'calendar.day_names_min.Wed',
      'calendar.day_names_min.Thu', 
      'calendar.day_names_min.Fri', 
      'calendar.day_names_min.Sat'
    ])
    .subscribe(translated => {
      this.en = {
        dayNamesMin: Object.keys(translated).map(key => translated[key])
      };
    });
}

It's important to note that the this.en variable won't have a value until the this.translateSvc.get() observable emits. Thus, you must consider that this.en is asynchronous when accessed.

For more information on handling async data, check here.

Alternatively, if you only intend to utilize the this.en variable in the template for displaying values, you can map the output from this.translateSvc.get() using the RxJS map operator and leverage the Angular async pipe.

Controller

en$: Observable<any>;

ngOnInit() {
  this.en$ = this.translateSvc.     // <-- assign the observable
    .get([
      'calendar.day_names_min.Sun', 
      'calendar.day_names_min.Mon', 
      'calendar.day_names_min.Tue', 
      'calendar.day_names_min.Wed',
      'calendar.day_names_min.Thu', 
      'calendar.day_names_min.Fri', 
      'calendar.day_names_min.Sat'
    ])
    .pipe(       // <-- transform the response here
      map(translated => ({ dayNamesMin: Object.keys(translated).map(key => translated[key]) }))
    );
}

Template

<ng-container *ngIf="(en$ | async) as en">
  {{ en.dayNamesMin | json }}
  {{ en.dayNamesMin[0] }}
  ...
  <p *ngFor="let day of en.dayNamesMin">
    {{ day }}
  </p>
</ng-container>

Update: Use with PrimeNg calendar

As demonstrated in the second approach, use the RxJS map operator to structure it into the required object format and incorporate it as input in the HTML template.

<ng-container *ngIf="(en$ | async) as en">
  <p-calendar 
    dateFormat="dd/mm/yy" 
    [(ngModel)]="value" 
    [locale]="en">   <!-- utilize `en` from the async pipe -->
  </p-calendar>
</ng-container>

How can I set an array as a property of an object using the Angular Subscribe method?

Answer №1

Update: Use with PrimeNg calendar

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