Why am I getting "Subscribe is not a function" error?

Question

I have a component that allows a user to select an option from the port list. Once they've made the selection, they click "Connect Port" button. this calls a service to store the selected port so that it can be stored as a string.

I am getting console logs that show the component is successfully calling the service and storing as it should. However, in any other component if I try to call the service with a subscribe; I get errors.

Port Service

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';

export interface Port {
  portName: String;
}

@Injectable({
   providedIn: 'root'
})
export class PortService {

activePort;

constructor() { }

setPort(port) {
  console.log('The port: ', port);
  this.activePort = port;
}

getPort(): Observable<Port> {
  console.log('The port for the application runtime: ', this.activePort);
   return this.activePort;
  }
}

App Component

import { Component, OnInit } from '@angular/core';
import { } from 'electron';
import * as Serialport from 'serialport';
import { SerialService } from './serial.service';
import { PortService, Port } from './core/port.service';
import { Observable } from 'rxjs';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {

  title = 'electron-angular-serialport';
  collapsed = false;
  connectedPort;

  constructor(private serial: SerialService, private port: PortService) {
    let isElectron: boolean = window && window['process'] && window['process'].type;

    if (isElectron) {
      let serialport: typeof Serialport = window['require']('serialport');
      let app: Electron.App = window['require']('electron').remote;
      console.log(serialport, app, window['process']);
    }
  }

  ngOnInit() {
    this.getPort();
  }

  getPort() {
    console.log('Getting Port');
    this.port.getPort().subscribe( data => this.connectedPort = data);
  }
}

I am really hoping that I can store this String "/dev/tty.usbmodem14201". So that I can use it throughout the app.

Answer 1

Your setPort didn't set the port as Observable, try transform the value to Observable

import {of} from 'rxjs'
...
setPort(port) {
  console.log('The port: ', port);
  this.activePort = of(port);
}