Module import in Ionic

Question

Module import in Ionic

I'm encountering an issue with Ionic, Angular, and TypeScript, and I'm feeling a bit lost...

I'm trying to call an external function from my file but I keep getting the following error: "Uncaught (in promise): TypeError: undefined is not an object (evaluating 'this.alertCtrl.create')"

Let's first take a look at my main file:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

import { params } from '../../modules/params';

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

  params = new params();

  constructor(public navCtrl: NavController) {
    this.params.popup("Hello", "test");
  }

}

And now, let's examine the page where the function is located:

import { AlertController } from 'ionic-angular';

export class params {
    public alertCtrl: AlertController;
    constructor(){

    }

    popup(title, text){
        let alert = this.alertCtrl.create({
            title: title,
            subTitle: text,
            buttons: ['OK']
        });
        alert.present();
    }
}

Where do you think I might be going wrong? Any help would be greatly appreciated. Thank you.

javascript angular typescript ionic-framework

Answer 1

Answer №1

In order for the injection to function correctly, it must be provided as a constructor parameter:

import { AlertController } from 'ionic-angular';

export class Params {
    constructor(public alertCtrl: AlertController) {

    }

    displayPopup(title, text){
        let alert = this.alertCtrl.create({
            title: title,
            subTitle: text,
            buttons: ['OK']
        });
        alert.present();
    }
}

Previously, you had declared a public property named alertCtrl of type AlertController, but it was not initialized, which resulted in the undefined error.

Answer 2

In order for the injection to function correctly, it must be provided as a constructor parameter:

import { AlertController } from 'ionic-angular';

export class Params {
    constructor(public alertCtrl: AlertController) {

    }

    displayPopup(title, text){
        let alert = this.alertCtrl.create({
            title: title,
            subTitle: text,
            buttons: ['OK']
        });
        alert.present();
    }
}

Previously, you had declared a public property named alertCtrl of type AlertController, but it was not initialized, which resulted in the undefined error.

Answer 3

Answer №2

Greetings, my friend.

To utilize a function in your Angular application, you must first include the @Injectable() decorator in the respective class. Here's an example of how to do it:

import { Injectable } from '@angular/core';
import { AlertController } from 'ionic-angular';

@Injectable()
export class CustomParams {

    constructor(public alertCtrl: AlertController){

    }

    popup(title, text){
        let alert = this.alertCtrl.create({
            title: title,
            subTitle: text,
            buttons: ['OK']
        });
        alert.present();
    }
}

Next, make sure to inject the variable in the constructor so you can call it on your page, like so:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

import { CustomParams } from '../../modules/custom-params';

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

    constructor(public navCtrl: NavController, public customParams: CustomParams) {
        this.customParams.popup("Hello", "test");
    }

}

I trust this explanation was beneficial to you! =)

Answer 4

Greetings, my friend.

To utilize a function in your Angular application, you must first include the @Injectable() decorator in the respective class. Here's an example of how to do it:

import { Injectable } from '@angular/core';
import { AlertController } from 'ionic-angular';

@Injectable()
export class CustomParams {

    constructor(public alertCtrl: AlertController){

    }

    popup(title, text){
        let alert = this.alertCtrl.create({
            title: title,
            subTitle: text,
            buttons: ['OK']
        });
        alert.present();
    }
}

Next, make sure to inject the variable in the constructor so you can call it on your page, like so:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

import { CustomParams } from '../../modules/custom-params';

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

    constructor(public navCtrl: NavController, public customParams: CustomParams) {
        this.customParams.popup("Hello", "test");
    }

}

I trust this explanation was beneficial to you! =)

Module import in Ionic

Answer №1

Answer №2

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