Ionic - Part 4

Details Arrow: Ionic 2

Today lets see how we can add details arrow or the right arrow icon to our list items in Ionic 2.

Ionic uses modes to customize the look of components. Each platform has a default mode, but this can be overridden. For example, an app being viewed on an Android platform will use the md (Material Design) mode. The < ion -app > tag(in index.html) will have class=”md” added to it by default and all of the components will use Material Design styles:

index.html

< ion-app class="md">

Default Modes used on different platforms
ios devices – ios mode.
android devices – md(Material Design) mode.
windows devices – wp mode.

ion-list item Right Arrow Icon: Ionic 2

YouTube Link: https://www.youtube.com/watch?v=gCXS6gRuyvk [Watch the Video In Full Screen.]

In ios mode, buttons and anchor elements with ion-item attribute will display right arrow icon by default. If you want to remove this right icon you should add detail-none attribute to your elements.

Note:
1. For removing right arrow icon use detail-none attribute on your elements.
2. To add right arrow icon use detail-push attribute on your elements.

If the arrow still doesn’t display, you need to overriding some variables inside src/theme/variables.scss file.

For iOS Mode: iOS devices

$item-ios-detail-push-show: true;

For md mode: android devices

$item-md-detail-push-show: true;

For wp mode: Windows Devices

$item-wp-detail-push-show: true;

Important:
If you are previewing or testing your ionic 2 application using Chrome browser on Windows machine, then set variable $item-wp-detail-push-show also to true or else simply set the one applicable to your target device.

src/pages/home/home.ts

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
 
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {
  companies: any;
  constructor(public navCtrl: NavController) {
    this.companies = [
      {name: 'Microsoft', code: 1},
      {name: 'Apple', code: 2},
      {name: 'Google', code: 3},
      {name: 'Oracle', code: 4}
    ];
  }
}

src/pages/home/home.html

  < ion-list no-lines>
    < ion-item *ngFor="let company of companies" detail-push>
      {{company.name}}
    < /ion-item>
  < /ion-list>

For explanation of above code please watch: Basics of Page Component: Ionic 2 video tutorial.

Remove Lines From ion-list items
Add no-lines attribute to ion-list tag to remove the default linings from the list items displayed on the view.

Basic Navigation: Ionic 2

Today lets learn basics of navigation / routing in Ionic 2. Ionic 2 and Angular 2 makes use of navigation stack for its navigation system. i.e., we can push and pop views to and from navigation stack.

Forward Navigation: We push page reference of the page we want to navigate to.
Backward Navigation: We execute pop operation on navigation stack to remove the current view or top view.

Once we push a page reference of the page we want to navigate to, a back button or back arrow symbol is automatically added to the navigation bar and whenever user clicks on it, the pop operation is executed for us automatically.

Basic Navigation or Routing: Ionic 2

YouTube Link: https://www.youtube.com/watch?v=VC-drnHG8Gg [Watch the Video In Full Screen.]

Generating Page using Ionic 2 CLI(Command Line Interface)

ionic g page Second

ionic generate page Second

This command creates Second page for us – which will have a TypeScript page(class file or component), a template file and a sass file.

src/pages/home/home.ts

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import { SecondPage } from '../second/second';
 
 
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {
  constructor(public navCtrl: NavController) {}
  nextPage(){
    this.navCtrl.push(SecondPage);
  }
}

Here we import the SecondPage page. Next define nextPage method. When nextPage method is invoked, we push reference to the page we want to navigate to, to the NavController reference.

Important: Also make sure to import Second page inside src/app/app.module.ts file and specify the page reference inside declarations and entryComponents section.

src/pages/home/home.html

 < button ion-button (click)="nextPage();">
   Next Page
 < /button>

Here we invoke nextPage method when user clicks on ‘Next Page’ button. This should take the user to the second page. And the user will be presented with a back button in the second page, so that he or she can navigate back to the home page or the first page again – which calls pop method on NavController reference automatically.

Set Root Page

this.navCtrl.setRoot(SecondPage);

using setRoot method, and passing the page reference of the page you want to set as root page, you can set the root page dynamically.

src/pages/second/second.ts

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
 
@Component({
  selector: 'page-second',
  templateUrl: 'second.html'
})
export class SecondPage {
  constructor(public navCtrl: NavController) {
    this.navCtrl.setRoot(SecondPage);
  }
}

Next Video Tutorial
In the next video tutorial we shall learn to pass data between pages while navigating.

Remove Element On Click: Ionic 2

This is a basic example wherein we have a list of company names and once the user clicks on individual name, that name gets removed from the list. We’ve not included the http calls and database in this example to keep things simple and minimalistic.

Remove Element On Click: Ionic 2

YouTube Link: https://www.youtube.com/watch?v=ZkHQXqFa0I0 [Watch the Video In Full Screen.]

src/pages/home/home.ts

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
 
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {
companies: Array< {}>;
  constructor(public navCtrl: NavController) {
    this.companies = [
      {name: 'Microsoft', code: 1},
      {name: 'Apple', code: 2},
      {name: 'Google', code: 3},
      {name: 'Oracle', code: 4},
      {name: 'IBM', code: 5}
    ];
  }
  remove(no){
    (this.companies).splice(no, 1);
  };
}

Here we have an array variable called companies, which has 5 company names in object format. We also have a method called remove which takes 1 parameter. This parameter is the index number of the item being clicked by the user. Once we get this index number we make use of JavaScript’s splice() method and remove the element from the array. Splice takes 2 arguments, the first one being the index(or the position) of the element to be removed and the second argument is the number of elements to be removed from position of the index received.

src/pages/home/home.html

< ion-list no-lines>
  < ion-item *ngFor="let company of companies; 
                     let i = index;" 
             (click)="remove(i);">
     {{company.name}}
  < /ion-item>
< /ion-list>

Here we assign index value to a variable i. We then pass this value of i to remove method once the user clicks on an item. i.e., we pass the index value of the item being clicked by the user, to the remove method.

Real-time Applications
In real-time applications we’ll pass a unique id of the clicked element to the remove method, which is then passed on to some http calls, which removes the item from the database(usually) and if the remove operation is successful we’ll remove the item from the User Interface using JavaScripts Splice() method. And if the remove operation fails, we’ll display appropriate message to the user.

ngIf, index, first, last: Ionic 2

Today lets see how we can track the index number of the loop. i.e., the number of completed iterations in a loop. We shall also learn *ngIf conditional operator and its usage.

Related Read:
Basics of Page Component: Ionic 2

*ngIf Conditional Operator

ngIf is called conditional operator because it operates based on conditions i.e., if the conditional statement it has been assigned is true, then the node it is attached to will be rendered or else it’ll not. *ngIf takes boolean values.

Example: If *ngIf is attached to a div and the condition is false, then the div it has been attached to won’t be added to the DOM. If the condition is true, then div is added to the DOM.

Video Tutorial: ngIf, index, first, last: Ionic 2

YouTube Link: https://www.youtube.com/watch?v=Cb4a-oh_yXM [Watch the Video In Full Screen.]

index, first, last
While we are looping through some array elements inside template file we can know the index of the loop using index variable. We can use ngIf and do something at the first iteration using first variable and similarly we can know the last iteration using last variable.

Source Code: src/pages/home/home.ts


  
    {{i+1}}. {{company.name}}  
     - Am last!
     - Am first

inside *ngFor we have initiated and assigned index value to variable i, last index value to variable lst and first index value to variable fst.

Inside ion-item we are using *ngIf to check if the iteration is first iteration, if so add ‘Am first’ message besides the first list item i.e., beside Microsoft. We also check if the iteration is a last iteration, if so we display ‘Am last!’ message beside the last item in the list i.e., beside IBM.

Output:

Microsoft – Am first
Apple
Google
Oracle
IBM – Am last!