How to return data after stream was subscribed?

Question

How to return data after the stream was subscribed? For example, I get URL in subscription, and then I want to return the stream with data based on this URD

public get() {
    this.service.getData().subscribe((data: any) => {
        // data was setted here
        this.url = data;
    });

    return this.http.get(this.url)
        .map(r => {
            ...
            return obj;
        });
}

Answer 1

You should use concatMap (or mergeMap) for this and turn this into a chain:

public get() {
  this.service.getData().do((data: any) => {
      // data was set here
      this.url = data;
    })
   .concatMap(data => this.http.get(data))
   .map(r => {
     ...
     return obj;
    });
}

Or maybe you don't even need to be using this.url (I don't know what's your use-case).

public get() {
  this.service.getData()
   .concatMap(url => this.http.get(url))
   .map(r => {
     ...
     return obj;
    });
}