title: Angular 8 RXJS - Make multiple HTTP calls sequentially
body: <p>My code is:</p>
  
  <pre><code>return this.creaClienti(cliente)
        .pipe(
          tap(res =&gt; console.log('Cliente -&gt;', res)),
          concatMap(res =&gt; this.creaIntolleranza(intolleranza)),
          tap(res =&gt; console.log('Intolleranza -&gt;', res)),
          concatMap(res =&gt; this.creaSpaziUtilizzati(utilizzoSpazi)),
          tap(res =&gt; console.log('Utilizzo spazi -&gt;', res)),
          concatMap(res =&gt; this.creaEvento(evento))
        );
    }
  </code></pre>
  
  <p>but this.creaClienti(cliente) is:</p>
  
  <pre><code> creaClienti(clienti: any[]): Observable&lt;any&gt; {
      return from(clienti).pipe(
        concatMap(cliente =&gt; &lt;Observable&lt;any&gt;&gt;this.http.post(environment.baseUrl + 'api/json/node/cliente', cliente, this.httpOptions))
      );
    }
  </code></pre>
  
  <p>the problem is that every time a contained call is ended the pipe restarts...</p>
  
  <p>I need to run multiple call lists sequentially, all the functions that are in the concatMap are in fact similar to <strong>creaClienti</strong></p>