Angular 6 Form not passing variable to URL

I am trying to create a form in angular that takes a name, passes it to a URL, and returns a portion of a .json file. I can't figure out why the url is not getting updated though.

The HTML:

<form (ngSubmit)="processForm($engineer)">
         <div class="form-group">
            <label for="engineerselectform">Engineer Name</label>
            <select class="form-control" id="engineerselectform" name="engineer" [(ngModel)]="engineer">
            <option></option>
            <option>Smith</option>
            <option>Jones</option>
            <option>Clark</option>
        </select>
    </div>

    <input class="btn btn-primary" type="submit" value="submit"  aria-pressed="true">
</form>

The Component:

import { Component, OnInit } from '@angular/core';
import { ScheduleService } from '../schedule.service';
import { ActivatedRoute } from '@angular/router';

@Component({
  selector: 'app-schedule',
  templateUrl: './schedule.component.html',
  styleUrls: ['./schedule.component.scss']
})
export class ScheduleComponent implements OnInit {
  engineer;

  constructor(
    private scheduleService: ScheduleService,
    private route: ActivatedRoute
    ) { }

  ngOnInit() {}
    processForm(engineer: string) {
      this.route.params.subscribe(params=> { const engineer = params["engineer"];
      this.scheduleService.getschedule(engineer).subscribe(engineer => this.engineer = engineer);
    });
  }
}

The Service:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable({
  providedIn: 'root'
})
export class ScheduleService {
  apiUrl ='http://127.0.0.1:5000/schedule'
  engineer;

  constructor(private http: HttpClient) { }

  getschedule(engineer: string){
    return this.http.get(`${this.apiUrl}?engineer=${this.engineer}`);
  }
}

The Flask API backend:

@app.route('/schedule', methods = ['GET'])
def engineer_location_api():
    if "engineer" in request.args:
        print ('did this')
        engineer_name = request.args["engineer"]
        print ("engineer name:", engineer_name)
    else:
        return "not found, sorry"

    answer = {}
    with open(LOC1, "r") as file:
        check_loc1 = json.load(file)
        for item in check_loc1["LOC1"]:
            if engineer_name in item["Engineer"]:
                answer.update(item)
            else:
                continue
    with open(LOC2, "r") as file:
        check_loc2 = json.load(file)
        for item in check_loc2:
            if engineer_name in item:
                answer.update(item)
            else:
                continue

    if answer:
        return answer
    else:

        return 'engineer not found'

app.run()

the error:

ERROR 
Object { headers: {…}, status: 200, statusText: "OK", url: "http://127.0.0.1:5000/schedule?engineer=undefined", ok: false, name: "HttpErrorResponse", message: "Http failure during parsing for http://127.0.0.1:5000/schedule?engineer=undefined", error: {…} }
core.js:6014:19

As I understand it, when I hit submit the process form function should send the engineer variable to the component where it sets it as a parameter that it provides to the service which should fill out the URL. But regardless of how I play around with it, the engineer always comes back as undefined. Clearly I'm missing something core to passing the variable.

Also, I'm super new and therefore there are probably other things in this code that are ugly or not best practice, feel free to rip into it, I figure my understanding can only go up.