Angular两个api请求和Promise问题

Question

I'm using some ugly api and agly database. And i must to "merge data" from two tables books and authors in angular service in my app. I have in my service two promises:

getBookData() {
    promise = new Promise((resolve, reject) => {
    this.http.get(
      `http://${that.serverAdress}/api/books`,
      that.headers
    ).subscribe((dataBooks: any) => {

// One of data records fields is data.author_id contains raw author id value (api is ugly and i cant fix it)

// All what i need is mix/merge or nesting this two promises for bind (replace) data.author_id to dataAuthor.name  

//exaple record of dataBooks
//0:{name: "Romeo And Julia", aurhor_id = 2}

//i need on output:

//0:{name: "Romeo And Julia", aurhor_id = "William Shakespeare"}

//using this function and getAuthorBy(aurhor_id). This is all my prblem. 

  resolve(dataBooks);
    }, error => {
      reject(error);
    });
  });
  return promise;
}


//and other promise returns author data  (specified by id)


getAuthorBy(id) {
  promise = new Promise((resolve, reject) => {
    this.http.get(
      `http://${that.serverAdress}/api/authors/${id}`,
      that.headers
    ).subscribe((dataAuthor: any) => {



     resolve(dataAuthor);
    }, error => {
      reject(error);
    });
  });
  return promise;
}

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Answer 1

If I understand the task correctly you can use forkJoin() to get data at once from several requests.

forkJoin(observable1$, observable2$).subscribe(([observable1, observable2]) => {
    // work with the observables
});