I am pulling values form apex method to display in the lightning combo box. I get 500 internal server error from the console log and i see the method name and class name are correct. Not sure where i am missing.

import { LightningElement, wire, track } from 'lwc';
import getDivisions from '@salesforce/apex/TrafficReportController.getDivisions';

export default class TrafficHistoryReport extends LightningElement {
    @track divisionvalue = '';   
    @track Divisionvalues = [];
            for(let i=0;i < data.length;i++){
                    label: data[i],
                    value: data[i]
            //this.divisionoption = this.Divisionvalues;
        else if (error){

    get divisionoption() {
        return this.Divisionvalues;




public with sharing class TrafficReportController {
    public TrafficReportController() {


    @AuraEnabled (cacheable=true)    
    public static List<String> getDivisions(){
       List<Division__c> LstDivisions = [Select id, Name from Division__c];
       List<String> Lststrings = new Lststrings();
       for(Division__c Div:LstDivisions){
       return Lststrings;


    <div>Traffic History Report</div>
        <lightning-combobox name="Divisions" label="Divisions" placeholder="Select a Division" value={divisionvalue} options={divisionoption} onchange={handlechange}></lightning-combobox>

  • I'm sure there's more to the error message aside from a simple 500 internal error. Check the Chrome console (dig into the object spit out) and set up user debugs / trace flags for the dev console for logs coming out of the dev console. Commented Dec 5, 2019 at 18:48
  • 1
    I had the List<String> Lststrings = new Lststrings(); defined wrong and VScode did not error. Also i was trying to test in local development environment. I tried to deployed in my org and the error came up. I was able to fix this issue. Now a new issue is duplicate item in the combo box. Need to figure iout how to save Label and ID in value so that each dropdown is unique.
    – Rajesh
    Commented Dec 5, 2019 at 19:41

1 Answer 1


You need to restart the list every time you get a new set of data (wire events can trigger more than once).

ListDivisions({data,error}) {
        this.Divisionvalues = data.map(record => ({ label: record.Name, value: record.Id }));
    } else {

You should be using ID values instead of the name for the options:

@AuraEnabled (cacheable=true)    
public static Division__c[] getDivisions(){
   return [Select id, Name from Division__c];
  • Thanks. I am planning to have a dynamic combo box using this combo box value. Can you please provide me some reference on how to do it?
    – Rajesh
    Commented Dec 6, 2019 at 0:40
  • Debug log shows the query is executed in the backend but in the front end, i see the list populated only if i navigate to different tab and come back. on load the list does not show any value.
    – Rajesh
    Commented Dec 10, 2019 at 17:43
  • @Rajesh Do not use "push", or it may not work. Note specifically I use Array.map instead to convert the values to a new Array and assign it to the attribute. This triggers a rerender and allows the values to show immediately.
    – sfdcfox
    Commented Dec 10, 2019 at 19:13
  • it worked. Thanks.
    – Rajesh
    Commented Dec 10, 2019 at 21:20

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