Angular2 How to get all selected check boxes

Question

So I am working on an Angular2 application. I have a table where each record represent a student and includes a checkbox

<input class="mycheckbox" type="checkbox" [value]='student.StudentId'>

At some point user will click on a button that needs to get the value of all selected check-boxes.

I am not sure who should I address this.

One idea is that each student will have a value of checked or not. And this has to be done through two-way bindings.

However this will imply that each time u have to go through all students

Is this the best available option ? And is there something that matches the following JQuery:

$('.mycheckbox:checked').each(function(){

Answer 1

I recently answered a similar question: https://stackoverflow.com/a/34142740/215945

You could do the following in your template:

<input class="mycheckbox" type="checkbox" [(ngModel)]="student.selected">{{student.StudendId}}

Then, to do something with the selected students:

this.students.filter(_ => _.selected).forEach(_ => { ... })

Answer 2

Another way to do the same is like this:

.html

<button value="all" (click)="bulk('all')">ALL</button>
<button value="none" (click)="bulk('none')">NONE</button>

<div *ngFor="#students of student_list #i=index">
  <input type="checkbox" value={{students.id}} class="checkedStudent"   
  (change)="checkedStudents(students.id)" id={{students.id}}>
</div>

in .ts file

abc:Array<any>= [];
checkedStudents(value) {
        console.log(value);
        if ((<HTMLInputElement>document.getElementById(value)).checked === true) {
            this.abc.push(value);
        }
        else if ((<HTMLInputElement>document.getElementById(value)).checked === false) {
            let indexx = this.abc.indexOf(value);
            this.abc.splice(indexx,1)
        }
        console.log(this.abc)
    }

// for Bulk actions

bulk(a) {
        // console.log(a);
        if (a == "all") {
            console.log("yes all");
            this.abc = [];
            for (let i = 0; i < this.student_list.length; i++) {
                (<HTMLInputElement>document.getElementsByClassName("checkedStudent")[i]).checked = true;
                this.abc.push(this.student_list[i].id);
            }
        }
        if (a == "none") {
            for (let i = 0; i < this.student_list.length; i++) {
                (<HTMLInputElement>document.getElementsByClassName("checkedStudent")[i]).checked = false;
            }
            this.abc = [];
        }
        console.log(this.abc);
    }

Answer 3

Simply add a conditional to the button and remember to check the 'value' of the checkbox field as follows:

<form 
    #f="ngForm"  
    (ngSubmit)="onSubmit(f.value)" >

    <div class="form-group">

        <h2>Enter Email for Newsletter :</h2> <br/>

        <input 

            #registrationemail="ngForm"
            ngControl="registrationemail" 

            placeholder="Email Address"
            required type="email" 
            class="form-control" 
            pattern="^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$"  />

        <div *ngIf="registrationemail.touched && registrationemail.errors" class="alert alert-danger">
            <div  *ngIf="registrationemail.errors.required" >An Email is required</div>
            <div  *ngIf="registrationemail.errors.pattern">Email is invalid</div>
        </div>

    </div>

    <div class="form-group">


        <input 
        id="accepttermsconditions"
        #accepttermsconditions="ngForm"
         ngControl="accepttermsconditions" 
        type="checkbox" 
        checked/>
        <label for="accepttermsconditions">Accept Terms and Conditions </label> 
        </div>

    <button
       [disabled]="!f.valid || 
        !accepttermsconditions.value"
      class="btn btn-primary" 
      type="submit">Submit </button>

</form>

Answer 4

You can also do it using 'formbuilder' in a simialr way to my prev. post as follows:

import {Component, OnInit} from '@angular/core';
import { FORM_DIRECTIVES, FormBuilder, ControlGroup } from '@angular/common';

@Component({
    selector: 'registration-form',
    directives: [FORM_DIRECTIVES],
    template: `

    <form 
    [ngFormModel]="myForm" 
        (ngSubmit)="onSubmit(myForm.value)" 
        class="ui form"> 

          <div class="form-group">
     <label for="registrationemailInput">EMail Address</label>  
     <input type="email"  
            required
            id="registrationemailInput" 
            placeholder="email address"  
            [ngFormControl]="myForm.controls['registrationemail']"
            class="form-control" 
            pattern="^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$"
             />


                <div *ngIf="myForm.controls['registrationemail'].touched && myForm.controls['registrationemail'].errors" class="alert alert-danger">
            <div  *ngIf="myForm.controls['registrationemail'].errors.required" >An Email is required</div>
            <div  *ngIf="myForm.controls['registrationemail'].errors.pattern">Email is invalid</div>
        </div>

            </div>

            <div class="form-group">
            <label for="termsandconditions">Accept Terms &amp; Conditions</label>
      <input  id="termsandconditions"
                type="checkbox"
                checked      
                [ngFormControl]="myForm.controls['accepttermsconditions']" 
                id="accepttermsconditions"
      />
      </div>

      <button 

       [disabled]="!myForm.valid || !myForm.controls['accepttermsconditions'].value"

            class="btn btn-primary"  
            type="submit">Submit</button>
     </form>`
})
export class FormbuilderComponent implements OnInit {

    myForm: ControlGroup;

    constructor(fb: FormBuilder) {
        this.myForm = fb.group({
            'registrationemail': ['test'],
            'accepttermsconditions': [true]
        })
    }

    ngOnInit() {
    }


    onSubmit(form: any): void {
        console.log('you submitted value:', form);
    }
}

Answer 5

PrimeNG DataTable has this as a built-in feature. Simply set selectionMode to multiple to get check box based selection. Live demo is at http://www.primefaces.org/primeng/#/datatableselection

Answer 6

1. I have just simplified little bit for those whose are using list of value Object. XYZ.Comonent.html.

<div class="form-group">
        <label for="options">Options :</label>
        <div *ngFor="let option of xyzlist">
            <label>
                <input type="checkbox"
                       name="options"
                       value="{{option.Id}}"

                       (change)="onClicked(option, $event)"/>
                {{option.Id}}-- {{option.checked}}
            </label>
        </div>
        <button type="submit">Submit</button>
    </div> 

** XYZ.Component.ts**. 2. create a list -- xyzlist. 3. assign values, I am passing values from Java in this list. 4. Values are Int-Id, boolean -checked (Can Pass in Component.ts). 5. Now to get value in Componenet.ts.

    onClicked(option, event) {
console.log("event  " + this.xyzlist.length);
console.log("event  checked" + event.target.checked);
console.log("event  checked" + event.target.value);
for (var i = 0; i < this.xyzlist.length; i++) {
    console.log("test --- " + this.xyzlist[i].Id;
    if (this.xyzlist[i].Id == event.target.value) {
        this.xyzlist[i].checked = event.target.checked;
    }
    console.log("after update of checkbox" + this.xyzlist[i].checked);

}