Ionic: How to not stack multiple toast notificatio

问题:

I got the following Ionic code fragment for displaying alarms / errors in an industrial App:

showError(message: string) {
  let toast = this.toastController.create({
      message: message,
      position: 'top',
      duration: 5000,
      cssClass: 'danger',
      showCloseButton: true
  });
  toast.present();
}

The App triggers the error message every time it detects a connection issues, which will be also roughly on a 5 second timer.

Multiple calls to this method will lead to 2 or more error messages shown on top of each other if the timing of this code is changed. Can I somehow detect that a toast is already being displayed? Also then, the 5000 msec timer would not be necessary and I can just remove the error message again when the connection is re-established.

Thanks and BR Florian

回答1:

You could store your Toast object in a variable outside your function, and call the dismiss() method before showing the next toast :

import { ToastController, Toast } from 'ionic-angular';


toast: Toast;    

showError(message: string) {
    try {
        this.toast.dismiss();
    } catch(e) {}

    this.toast = this.toastController.create({
        message: message,
        position: 'top',
        duration: 5000,
        cssClass: 'danger',
        showCloseButton: true
    });
    toast.present();
}

回答2:

Here my solution :-)

// ToastService.ts
import { Injectable } from '@angular/core';
import { ToastController, Toast } from 'ionic-angular';

@Injectable()
export class ToastService {

  private toasts: Toast[] = [];

  constructor(private toastCtrl: ToastController) {}

  push(msg) {
    let toast = this.toastCtrl.create({
      message: msg,
      duration: 1500,
      position: 'bottom'
    });

    toast.onDidDismiss(() => {
      this.toasts.shift()
      if (this.toasts.length > 0) {
        this.show()
      }
    })

    this.toasts.push(toast)

    if (this.toasts.length === 1) {
      this.show()
    }
  }

  show() {
    this.toasts[0].present();
  }

}

回答3:

You can check if there is already a toast present or not and create new only if no toast present.

import { ToastController, Toast } from 'ionic-angular';


toast: Toast;    
isToastPresent:boolean=false;

show(){

this.isToastPresent?'':this.showError('No network');

}

showError(message: string) {

    this.toast = this.toastController.create({
        message: message,
        duration: 3000,
        cssClass: 'danger',
        showCloseButton: true
    });
    toast.present();
     this.isToastPresent=true;

    this.toast.onDidDismiss(() => {
      this.isToastPresent=false;
      console.log('Dismissed toast');
    });

}

回答4:

In Ionic 4 Toast UI Component

Show Ionic 4 Toast only once using below code

// Call this method  
showOnceToast(){
  this.toastController.dismiss().then((obj)=>{
  }).catch(()=>{
  }).finally(()=>{
    this.manageToast();
  });
}

manageToast() {
  this.toastInstance = this.toastController.create({
    message: 'Your settings have been saved.',
    duration: 2000,
    animated: true,
    showCloseButton: true,
    closeButtonText: "OK",
    cssClass: "my-custom-class",
    position: "middle"
  }).then((obj) => {
    obj.present();
  });
}

Source Link : http://www.freakyjolly.com/ionic-4-adding-toasts-in-ionic-4-application-using-ui-components-with-plugins/