Getting empty data from Apex method that returns an SObject

Question

I've got an LWC component that calls an Apex method that creates an event, sends an email, and then returns a custom DTO object. The Apex method works with my test class but when I call it through the LWC, it always return an empty object.

Heres my LWC:

import { LightningElement, api } from 'lwc';
import { refreshApex } from '@salesforce/apex';
import  otJs from '@salesforce/resourceUrl/opentok';
import { loadScript } from 'lightning/platformResourceLoader';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';
import OpenTok from '@salesforce/apex/OpenTokViewController.sendNewSessionDetails';

export default class VideoChatLinks extends LightningElement {
    session;
    @api recordId;
    
    renderedCallback() {
        // ....
        
    }

    handleError(error) {
   // .......
    }
    
    videoBySMS() {
        console.log('videoBySMS clicked');
        this.getOTSession('sms');
    }

    videoByEmail() {
        console.log('videoByEmail clicked');
        this.getOTSession('email');
    }

    getOTSession(via) {
        OpenTok({via: via, contactId: this.recordId})
        .then((data) => {
            if (data) { **// data is always {}**
               this.session = data;
               if (this.session && this.session.sessionId) { **//This always false b/c data is {} **
                   this.initializeSession(this.session.apiKey, this.session.sessionId);
               } else {
                   this.handleError('Session data could not be retrieved');
               }
             } else {
                this.handleError('Session not created. Check the logs for details');
             }
        })
        .catch(error => {
            this.handleError(error);
        });
    }

    initializeSession(apiKey, sessionId) {
       // .....
    }
}

The Apex code :

public class OpenTokViewController {
  @AuraEnabled()
  public static OpenTokSessionDTO sendNewSessionDetails(String via, Id contactId) {
    //create an OpenTokSession and return the data needed.
    return new OpenTokSessionDTO(session.sessionId, session.apiKey);
  }
}

public with sharing class OpenTokSessionDTO {
    public String sessionId { get; set; }
    public Integer apiKey { get; set; }
    public OpenTokSessionDTO(String sessionId, Integer apiKey) {
        this.sessionId = sessionId;
        this.apiKey = apiKey;
    }
}

Answer 1

Since OpenTokSessionDTO is a custom class, you will need to make its properties accessible and serializable by the Aura/Lightning framework:

public with sharing class OpenTokSessionDTO {

    @AuraEnabled 
    public String sessionId { get; set; }
    @AuraEnabled 
    public Integer apiKey { get; set; }

    public OpenTokSessionDTO(String sessionId, Integer apiKey) {
        this.sessionId = sessionId;
        this.apiKey = apiKey;
    }
}