Angular is patiently awaiting the completion of the subscription

Currently, I am in the process of developing a test application using Angular. The challenge arises when I attempt to retrieve data through a Get request and then return a value based on that data. The code snippet below outlines the scenario:

public getNextId(entityName: string): number {
    console.info('Retrieving next ID for  ' + entityName);

    let seqId: SeqId;

    const url = `${this.apiURL}/${entityName}`;

    console.info('SeqID URL: ' + url);

    this.http.get<SeqId>(url)
        .subscribe((data: SeqId) => seqId = data); -> 1

    /*Do something with seqId */ -> 2

    return seqId.nextEntityId;
}

The issue at hand is that step (2) is executed before step (1). This results in the seqId variable not being properly set by the time step (2) is reached.

I am seeking guidance on how to effectively conduct a Get operation, process the retrieved data, and return a value within the same method. Any assistance on this matter would be greatly appreciated.

Thank you in advance.

Answer №1

To improve your code, ensure that you are returning an observable instead of subscribing directly

  fetchData() {return this.httpClient.fetchUrl<SeqId>(apiUrl)
    .pipe(map(result: SeqId) => sequenceId = result); 
}

Then, in the controller, subscribe to the fetchData method and perform the necessary actions

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