RxJS sequence equivalent to promise.then()?

Question

I used to develop a lot with promise and now I am moving to RxJS. The doc of RxJS doesn\'t provide a very clear example on how to move from promise chain to observer sequenc

Answer 1

This is how I did it.

Previously

  public fetchContacts(onCompleteFn: (response: gapi.client.Response) => void) {
    const request = gapi.client.people.people.connections.list({
      resourceName: 'people/me',
      pageSize: 100,
      personFields: 'phoneNumbers,organizations,emailAddresses,names'
    }).then(response => {
      onCompleteFn(response as gapi.client.Response);
    });
  }

// caller:

  this.gapi.fetchContacts((rsp: gapi.client.Response) => {
      // handle rsp;
  });

After(ly?)

public fetchContacts(): Observable> {
    return from(
      new Promise((resolve, reject) => {
        gapi.client.people.people.connections.list({
          resourceName: 'people/me',
          pageSize: 100,
          personFields: 'phoneNumbers,organizations,emailAddresses,names'
        }).then(result => {
          resolve(result);
        });
      })
    ).pipe(map((result: gapi.client.Response) => {
      return result; //map is not really required if you not changing anything in the response. you can just return the from() and caller would subscribe to it.
    }));
  }

// caller

this.gapi.fetchContacts().subscribe(((rsp: gapi.client.Response) => {
  // handle rsp
}), (error) => {
  // handle error
});