Typescript Error when calling a function with observable

Getting the following error when running ionic serve:
Typescript Error
Expected 1 arguments, but got 0.

It also highlights this line in the code:

The code will function properly via the browser (refrbut wont compile for mobile.

Here is my Code Page:
import { Component } from ‘@angular/core’;
import { IonicPage, NavController, NavParams } from ‘ionic-angular’;
import { Http } from ‘@angular/http’;
import xml2js from ‘xml2js’;
import { SearchProvider } from ‘…/…/providers/search/search’
import { CallNumber } from ‘@ionic-native/call-number’;

selector: ‘page-results’,
templateUrl: ‘results.html’,

export class ResultsPage {

employees$: SearchProvider[]

constructor(public navCtrl: NavController, public navParams: NavParams, public search: SearchProvider, private callNumber: CallNumber) {
this.employees$ = [];

var employees;
.subscribe(data => {
xml2js.parseString(data.text(), function (err, result) {
employees = result.qdbapi.record;
return data;
this.employees$ = employees;
console.log (this.employees$);
return data;

@ewehrmann Well, you have your answer in the error:

You have:

import { SearchProvider } from ‘…/…/providers/search/search’

You inject it with public search: SearchProvider, and then you use it like:

this.search.getEmployees().subscribe(data => ...)

You aren’t passing any parameters to getEmployees() like getEmployees(someValue).

Look at your class SearchProvider and see what it expects in getEmployees.

export class SearchProvider {

    getEmployees(someParam: SomeType) {
        // do some stuff


I don’t know what is in your provider, but should be similar to the above.

As a side note, you have employees$: SearchProvider[]. I don’t know exactly why you have this but I think you shouldn’t have an array of providers (normally, providers should be injected).

Additionally, the chicanery involving employees is a hideous mix of rx and callbacks. It would look much cleaner if you found (or wrote) a shim that looks something like this:

parseXmlEmployees(xml: string): Observable<Employee[]> {
  return Observable.create((obs) => {
    xml2js.parseString(xml, (err, result) => {

…that way you can use switchMap cleanly like so:

getEmployees(): Observable<Employee[]> {
  return this.oldGetEmployees().pipe(
    switchMap(xml => this.parseXmlEmployees(xml)));
1 Like

Thanks! I had the variable in the constructor of the provider so I guess I didn’t need to pass it into the function.