Emulate extended interaction in Angular 2

For educational purposes, I am looking to simulate a lengthy response from the server in Angular 2. Here is the code snippet:

getTasks() : Observable<Task[]> {
    return this.http.get('data/tasks.json').map(response =>  {
        return response.json();
    });
}

// implementing 
getTasks().subscribe(groups => {
   this.tasks = groups;
});

I require the server response to take at least 1 second. In Angular 1.5, I achieved this like so:

 this.getTasks = function () {
    return $http.get("data/tasks.json").then(function (response) {
        return $timeout(function () {
            return response.data;
        }, 1000);
    };
}

In Angular 2, following suggestions from this post, I attempted:

getTasks() : Observable<Task[]> {
    return this.http.get('data/tasks.json').map(response =>  {            
        return Observable.of(response.json()).delay(1000);
    });
}

and

getTasks() : Observable<Task[]> {
    return this.http.get('data/tasks.json').map(response =>  {
       return Observable.create((obs: Observable<Task[]>) => {
            obs.next(response.json());
            obs.complete();
       ).delay(1000);        
    });
}

However, I am encountering TypeScript compilation errors or receiving an Observable instead of a task collection when using getTasks().subscribe. It seems like I might be overlooking something. Any assistance would be greatly appreciated. Thank you.

Answer №1

The issue arises from a mismatch in types. In the getTasks method, the return type is supposed to be Observable<Task[]>. However, the map method is returning an observable instead of an array (of type Task[]). To resolve this error, simply return the observable as usual and then apply the delay method to postpone the emission of the observable.

getTasks() : Observable<Task[]> {
    return this.http.get('data/tasks.json').map(response =>  {
       return response.json();  
    })
    .delay(1000);
}

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