How do I change data in my notification with a promise?

I have created a notification that is scheduled every minute just to test it. It’s working perfectly fine. I’m looking for a way to update the notification every time it is called making it show new data every time. I haven’t been able to figure out how to do it. I have tried a few different apporaches with the update but nothing seems to work.

I’m using Ionic 3 and Angular 4.

The testNotification function is the one in question. Here is my entire typescript for the page:

import { Component } from '@angular/core';
import { NavController, NavParams, Platform, AlertController } from 'ionic-angular';
import { LocalNotifications } from '@ionic-native/local-notifications';

// Service import for items
import { ItemApi } from '../../services/service';

@Component({
  selector: 'page-notification',
  templateUrl: 'notification.html',
})
export class NotificationPage {

  // Define the variables used in the view
  notifications: any[] = [];
  items: any;
  oneItem: any;
  public buttonClicked: boolean = true;
  
  // The constructor initializes the imports
  constructor(
              public navCtrl: NavController, 
              public navParams: NavParams,
              public platform: Platform,
              public alertController: AlertController,
              public localNotifications: LocalNotifications,
              private itemApi: ItemApi
              ) 
              {}

    // --------------------------------------------------------------------------------------
    // ---- FUNCTIONS
    // -------------------------------------------------------------------------------------- 
    
    // This is where the data loads from the service.
    // It happens when the view loads for the first time.
    ionViewDidLoad() {

        // Get the JSON data from our itemApi
        this.itemApi.getItems().then(data => {

            this.items = data;

            let randomNumber = Math.floor(Math.random() * this.items.length)
            
            // Select the random object an pass it to the oneItem object
            this.oneItem = this.items[randomNumber];

        });

    }

    // --------------------------------------------------------------------------------------
    // ---- Main notification function
    // -------------------------------------------------------------------------------------- 
    
    testNotification() {

            // The notification
            let notification = {
                id:1,
                title: this.oneItem.word,
                text: this.oneItem.description,
                every: "minute"
            };

            this.notifications.push(notification);
            
            if(this.platform.is('cordova')){
 
                    // Cancel any existing notifications
                    this.localNotifications.cancelAll().then(() => {
            
                        // Schedule the new notifications
                        this.localNotifications.schedule(this.notifications);
            
                        this.notifications = [];
            
                        let alert = this.alertController.create({
                            title: 'Notifications set',
                            buttons: ['Ok']
                        });
                        
                        // Initializes the alert
                        alert.present().then(() => {
                            
                                // Get the JSON data from our itemApi
                                this.itemApi.getItems().then(data => {

                                this.items = data;

                                let randomNumber = Math.floor(Math.random() * this.items.length)
                                
                                // Select the random object an pass it to the oneItem object
                                this.oneItem = this.items[randomNumber];

                        });

                        // The notification is updated
                        this.localNotifications.update(notification = {
                            id:1,
                            title: this.oneItem.word,
                            text: this.oneItem.description,
                            every: "minute"
                        });

                        });

            
                    });
            
                }

    }
    // End of notification
    
    // --------------------------------------------------------------------------------------
    // ---- CancelAll notifcations in a function.
    // --------------------------------------------------------------------------------------
   
    cancelAll(){

      this.localNotifications.cancelAll();
 
      let alert = this.alertController.create({
          title: 'Notifications cancelled',
          buttons: ['Ok']
      });
  
      alert.present();
 
    }
    // End of cancelAll function



    // --------------------------------------------------------------------------------------
    // ---- A function called on the back button to go back
    // -------------------------------------------------------------------------------------- 
    goBackButton(){

        // Go back one view in the navigation stack
        this.navCtrl.pop();

        // Hide the element just when it is clicked
        this.buttonClicked = !this.buttonClicked;
    }
    

}

Do you have any idea how to solve this?

Thanks!