Angular - Button not incrementing variable

Question

I'm pretty new to Angular and am having trouble incrementing and decrementing my variable using a button. I've looked around on here and tried what I've found and it doesn't seem to work. I'm trying to use the buttons, Next and Previous, to either add 1 or subtract 1 from my selectedEmployee variable and dynamically change what's output onto the screen.

Edit The Next function works as long as I don't select something from the combobox, it just adds 1 to the initialized 0 but doesn't work if I select something from the combobox. But, the Previous function works all of the time. Why would there be this difference? Also, the next function does work after I have used the previous function, but it just doesn't work the initial time after selecting an item from the combo box.

Here's my tracker.component.ts:

import { Component, OnInit, Input } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

import { EmpInfoService } from './emp-info.service';
import { EmpInfo } from './emp-info'; 

@Component({
    selector: 'pto-tracker',
    templateUrl: `./tracker.component.html`,
    styleUrls: ['./tracker.component.css']
})

export class TrackerComponent implements OnInit{
    empInfo: EmpInfo[];
    isHidden: boolean = false;
    public selectedEmployee: number = 0;

    constructor(private empInfoService: EmpInfoService) { }

    getEmpInfo(): void {
        this.empInfoService.getEmpInfos().then(
            empInfo => this.empInfo = empInfo
        );
    }

    ngOnInit(): void {
        this.getEmpInfo();
    }

    toggleSummary(): void {
        this.isHidden = !this.isHidden;
    }

    nextEmployee(): void {
        this.selectedEmployee = this.selectedEmployee + 1;
    }

    previousEmployee(): void {
        this.selectedEmployee = this.selectedEmployee - 1;
    }
}

and here's my tracker.component.html:

<div class="row">
  <div [ngClass]="{'col-xs-12':isHidden === true, 'col-xs-7': isHidden !== false}" style="background-color:red;">
    <button class="form-control" style="width:150px;" (click)="toggleSummary()">Open Summary</button>
    <select id="empName" [(ngModel)]="selectedEmployee">
      <option selected="selected" disabled>Employee Name...</option>
      <option *ngFor="let emp of empInfo; let i = index" [value]="i">{{i}} - {{emp.EmpID}}</option>
    </select>
    <select id="PTOtype">
      <option selected="selected" disabled>Type of PTO...</option>
      <option value="PTO">PTO</option>
      <option value="ETO-Earned">ETO - Earned</option>
      <option value="ETO-Used">ETO - Used</option>
      <option value="STDLTD">STD/LTD</option>
      <option value="Uncharged">Uncharged</option>
    </select>
    <h2 *ngIf="empInfo && empInfo.length > selectedEmployee">{{empInfo[selectedEmployee].FirstName}}</h2>
    <button class="form-control" style="width: 150px;" (click)="nextEmployee()">Next</button>
    <button class="form-control" style="width: 150px;" (click)="previousEmployee()">Previous</button>
  </div>
  <div *ngIf="isHidden" class="col-xs-5">
        <pto-summary [selectedEmployee]="selectedEmployee"></pto-summary>
  </div>
</div>

Any help is greatly appreciated. Thanks in advance!

score 3 · Answer 1 · answered Jun 02 '17 at 14:35

3

Set selectedEmployee to 0

public selectedEmployee: number = 0;

answered Jun 02 '17 at 14:35

Lucas

9,871
5
42
52

that didn't work, whenever one of the buttons is hit, the sample text that I have displaying the variable just disappears – rcarcia02 Jun 02 '17 at 14:42
How many empInfo you have? as per empInfo && empInfo.length > selectedEmployee, It should disappear eventually... :)# – dipak Jun 02 '17 at 15:04

score 2 · Accepted Answer · edited Jun 02 '17 at 18:08

2

I think problem in your select binding, you can use [ngValue] instead [value] in select.

<select id="empName" [(ngModel)]="selectedEmployee">
   <option selected="selected" disabled>Employee Name...</option>
   <option *ngFor="let emp of empInfo; let i = index" [ngValue]="i">{{i}} - {{emp.EmpID}}</option>
</select>

i in this case will be string, so calculate on it will be error.

Read this topic for more info:

Binding select element to object in Angular 2

edited Jun 02 '17 at 18:08

AT82

71,416
24
140
167

answered Jun 02 '17 at 15:06

Thien Hoang

625
3
12

oh, right. that makes sense! thank you, that worked perfectly! – rcarcia02 Jun 02 '17 at 15:17

Angular - Button not incrementing variable

2 Answers2