Understanding the timing of records being returned via an Observable in Angular's ngOnInit

In my Angular 2 application, I am using an observable to keep track of an array of records.

As the results of this observable are stored in the variable "records", I am utilizing *ngFor="let record of records" to iterate over and display them in my view. Everything is functioning correctly as expected.

However, I am encountering an issue when trying to log the length of the array of records in a separate function, as it always returns "0".

Currently, I am performing these operations within the ngOnInit life cycle hook of Angular. Here is how it is implemented:

ngOnInit() {
    this.clientService.getAllClients()
        .subscribe(resRecordsData => this.records = resRecordsData,
        responseRecordsError => this.errorMsg = responseRecordsError);

    this.isActive();
}

Following the ngOnInit method, I have defined the isActive function like so:

isActive() {
    console.log('The total number of active records is ' + this.records.length);
}

It seems that the problem may be arising because "records" is not available at the time of the console log during OnInit. Is there a different approach I should take to retrieve the actual length of the array once "records" has been returned?

Answer №1

To retrieve the data stored in the success parameter of .subscribe(), you can still utilize an anonymous function; however, the way it is written must be adjusted as follows:

ngOnInit() {
    this.clientService.getAllClients()
        .subscribe(resRecordsData => { // take note of the curly braces
            this.records = resRecordsData;
            this.isActive();
        },
        responseRecordsError => this.errorMsg = responseRecordsError);
}

By adding the curly braces, you enable the use of multi-line anonymous methods.

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