How can you set subscribe data in an Angular 2 constructor?

Question

How can you set subscribe data in an Angular 2 constructor?

Currently delving into Angular 2, I find myself in need of assigning the data obtained from my service to a variable within the constructor of my component. How can I effectively utilize the subscribe function in order to assign these values to a public data array?

public data: Array<any> =[];

public constructor(private _languageService: LanguageService){

    this._languageService.getLanguages()
    .subscribe(languages => {this.languages = languages;}
        ,error => this.errorMessage = <any>error)

    this.length = this.data.length;
    //Is there a way for me to set this.data equal to this.languages 
    //if this.languages remains empty outside of the subscribe function?
}

I would greatly appreciate any assistance on how to effectively assign the returned data from a service to a variable.

typescript angular

Answer 1

Answer №1

All values must be assigned within the .subscribe() method

public data: Array<any> =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.languages =languages;
            [].push.apply(this.data, languages);
        },error => this.errorMessage = <any>error)

    ...
}

The code snippet [].push.apply(target, source) inserts incoming values into an existing array reference

EXPAND

Data can be loaded from an observable source and then consumed when available. Utilize *ngIf in the template

<div>
   <some-component
      *ngIf="myData"
       [bindSource]="myData"
       ...
   ></some-component>
</div>

In the component, we subscribe to retrieve the data:

public myData: any[] =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.myData = languages;
        });
}

Answer 2

All values must be assigned within the .subscribe() method

public data: Array<any> =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.languages =languages;
            [].push.apply(this.data, languages);
        },error => this.errorMessage = <any>error)

    ...
}

The code snippet [].push.apply(target, source) inserts incoming values into an existing array reference

EXPAND

Data can be loaded from an observable source and then consumed when available. Utilize *ngIf in the template

<div>
   <some-component
      *ngIf="myData"
       [bindSource]="myData"
       ...
   ></some-component>
</div>

In the component, we subscribe to retrieve the data:

public myData: any[] =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.myData = languages;
        });
}

How can you set subscribe data in an Angular 2 constructor?

Answer №1

Similar questions

Angular2 presents class definitions in a way that resembles initializers. The constructor() function, however, serves a distinct purpose. What sets them apart?

Template for typed variable - `ng-template`

How can I pass custom QueryParams to Router's NavigationExtras in Angular and create a personalized navigation experience?

Angular application unable to invoke the Web API GET method

Angular CLI build/serve/test commands task problem matcher in VS Code

Is there a way to verify if a user taps outside a component in react-native?

Setting up Bootstrap within an Angular application

Importing and declaring child components in Angular testing with Karma, Jasmine, and TestBed is essential for comprehensive component testing. This ensures all

Set the style of the mat-select element

What is the best way to add multiple elements to an array simultaneously?

Using an alias component in Angular 2 refers to a method of referencing components with

TypeScript NodeJS Error: Unable to access the 'address' property as it is undefined

Activating `routerLinkActive` for multiple components

Guide on setting up a redux store

Angular 5 npm build issue causing crash due to memory allocation imbalance (Allocation Rebalance failure - process exhausted memory)

Angular downgrades from version 13.3.8 to 13.3.7

What is causing this error/bug to show up in Angular?

Sharing screen content in Firefox using Angular 6

Is the environment file in Angular adequately protected from potential breaches?

Exploring the process of selecting checkboxes in Angular 6