When invoked, the function Subscribe() does not have a

Currently, I am facing an issue where I cannot use the result obtained from subscribe() outside of the subscribe function. Whenever I try to console.log the result, it always shows up as undefined. My suspicion is that this might be related to the asynchronous nature of the operation, but I'm unsure of how to resolve this. Would using a promise instead of subscribe() be a better approach in this scenario?

export class MyComponent implements OnInit {
    textt: String;

    constructor(private tstService: MyComponentService) { this.source = new LocalDataSource(this.data) }

    ngOnInit(): void {
        this.tstService.getTstWithObservable()
        .map(result => result.map(i => i.user.data))
        .subscribe(
           res => { this.textt = res[0].title; }
       );
    }

    data = [
        {
          title: this.textt,
          sdate: '01/04/1990',
          edate: '30/09/1990',
        },
      ];

    source: LocalDataSource;
}

Answer №1

It appears that the issue stems from the fact that the asynchronous nature of the subscribe function is causing problems. The variable data.title is not initialized during creation because this.textt is not yet assigned a value when the component is instantiated, and will be set at an undetermined time.

To resolve this, you have a couple options. You can either define and initialize the data attribute within the subscription block, or simply assign the value of title directly to it.

ngOnInit(): void {
    this.tstService.getTstWithObservable()
    .map(result => result.map(i => i.user.data))
    .subscribe(
       res => { 
           this.textt = res[0].title; 
           this.data.title = this.textt;
       }
   );
}

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