Checkbox value is not changing in reactive forms angular

Question

i m generating form from json file with help of reactive forms.Generation of form works properly but the problem i m facing is - when i click on checkbox for first time in mozila its value becomes "on". but when i uncheck it nothing is happening its value remains "On" which should be "off or false". In chrome on click nothing is happening.

app.components.ts

import { Component } from '@angular/core';
import { QuestionControlService } from './question-control.service';
import GxData from './gx.json';
@Component({
  selector: 'app-root',
  template: `
    <div>
      <app-dynamic-form [questions]="questions"></app-dynamic-form>
    </div>
  `,
  providers: []
})
export class AppComponent{

  questions: any[];
  constructor() {
    this.questions = GxData;
  }

}

dynamic-form.components.ts

import { Component, Input, OnInit, SimpleChanges } from '@angular/core';
import { FormGroup } from '@angular/forms';
import { QuestionControlService } from '../question-control.service';
import SbbData from '../sbb.json';
import GxData from '../gx.json';

@Component({
  selector: 'app-dynamic-form',
  templateUrl: './dynamic-form.component.html',
  providers: [QuestionControlService]
})
export class DynamicFormComponent implements OnInit {

  @Input() questions: any[] = [];
  form: FormGroup;
  payLoad = '';

  constructor(private qcs: QuestionControlService) { }

  ngOnInit() {
    this.form = this.qcs.toFormGroup(this.questions);
  }
  callGx() {
    this.questions = GxData;
    this.form = this.qcs.toFormGroup(this.questions);
  }
  callSbb() {
    this.questions = SbbData;
    this.form = this.qcs.toFormGroup(this.questions);
  }

  onSubmit() {

    this.payLoad = JSON.stringify(this.form.value);
    console.log(JSON.parse(this.payLoad));
  }

}

dynamic-form.component.html

<div class="search_box">
  <form (ngSubmit)="onSubmit()" [formGroup]="form">
      <button type="button" (click)="callSbb()">SBB</button> 
      <button type="button" (click)="callGx()">GX</button> 
    <div *ngFor="let question of questions" class="form-row">
      <app-question [question]="question" [form]="form"></app-question>
    </div>

    <div class="form-row">
      <button type="submit" [disabled]="!form.valid">Save</button>
    </div>
  </form>

  <div *ngIf="payLoad" class="form-row">
    <strong>Saved the following values</strong><br>{{payLoad}}
  </div>
</div>
{{form.value |json}}

question-control.service.ts

import { Injectable } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';

@Injectable()
export class QuestionControlService {
  constructor() { }

  toFormGroup(questions: any[]) {
    let group: any = {};

    questions.forEach(question => {
      group[question.key] = question.required ? new FormControl(question.value || '', Validators.required)
        : new FormControl(question.value || '');
    });
    return new FormGroup(group);
  }
}

dynamic-form-question.component.ts

import { Component, Input } from '@angular/core';
import { FormGroup } from '@angular/forms';

// import { QuestionBase } from '../question-base';

@Component({
  selector: 'app-question',
  templateUrl: './dynamic-form-question.component.html'
})
export class DynamicFormQuestionComponent {
  @Input() question: any;
  @Input() form: FormGroup;
  get isValid() { return this.form.controls[this.question.key].valid; }
}

dynamic-form-question.component.html

<div [formGroup]="form">


  <div [ngSwitch]="question.controlType" class="checkbox_wrapper">

    <input *ngSwitchCase="'textbox'" [formControlName]="question.key" [id]="question.key" [type]="question.type" name="{{question.name}}">
    <label [attr.for]="question.key">{{question.label}}</label>

    <select [id]="question.key" *ngSwitchCase="'dropdown'" [formControlName]="question.key" name = "{{question.name}}" >
      <option *ngFor="let opt of question.options" [attr.value]="opt.key" [selected]="opt.select">{{opt.value}}</option>
    </select>
  </div>
  <div class="errorMessage" *ngIf="!isValid">{{question.label}} is required</div>
</div>

both json-files look like

[
    {
        "key": "Context",
        "label": "Context",
        "required": false,
        "order": 1,
        "controlType": "textbox",
        "name": "Context",
        "type": "checkbox"
    },
    {
        "key": "contextopt",
        "label": "",
        "required": false,
        "order": 2,
        "controlType": "dropdown",
        "name": "contextopt",
        "options": [
            {
                "key": "All Context",
                "value": "All Context",
                "select": true
            },
            {
                "key": "aaa",
                "value": "aaa"
            },
            {
                "key": "bb",
                "value": "bb"
            },
            {
                "key": "Other",
                "value": "Other"
            }
        ]
    },
    {
        "key": "Movement",
        "label": "Movement",
        "required": false,
        "order": 3,
        "controlType": "textbox",
        "name": "Movement",
        "type": "checkbox"
    }
]

i don't see a checkbox in dynamic-form-question.component.html? — ysf
– ysf, Commented Jun 27, 2019 at 14:09
@ysf [type] = question.type decides it will be checkbox or something else. <input *ngSwitchCase="'textbox'" [formControlName]="question.key" [id]="question.key" [type]="question.type" name="{{question.name}}"> . its generated from json file. — Mandeep Singh
– Mandeep Singh, Commented Jun 27, 2019 at 14:13

Eliseo · Accepted Answer · 2019-06-27 16:27:12Z

4

Update the problem is when you write [type]="question.type" and question.type="checkbox". It's look like Angular not love this for checkbox, (but love if use email, number....)

Replace the ng*SwitchCase="'textbox'" for

<ng-container *ngSwitchCase="'textbox'">
<input  *ngIf="question.type!='checkbox'" [formControlName]="question.key"
        [id]="question.key" [type]="question.type">
<input *ngIf="question.type=='checkbox'" [formControlName]="question.key"
        [id]="question.key" type="checkbox">
</ng-container>

You can be the example in stackblitz

Other Idea is create a new type, "checkbox" and a new option of switchCase The new CheckBoxQuestion is copy of textbox

export class CheckBoxQuestion extends QuestionBase<boolean> {
  controlType = 'checkbox';

  constructor(options: {} = {}) {
    super(options);
  }
}

And the switchCase add

<input *ngSwitchCase="'checkbox'" type="checkbox" [formControlName]="question.key">

, in the stackblitz you has the two cases

NOTE: You're creating a large loop of

<div [formGroup]="form">
   <input formGroupName="question.key">
</div>
<div [formGroup]="form">
   <input formGroupName="question.key">
</div>
   ...

I suggest, change your dynamic-form-question.component.html to create simply

<div>
  <input [formControl]="form.get(question.key)" ..>
</div>

Yes, change the combination [formGroup]="form"..formControlName=".." by [formControl]="form.get(..").

edited Jun 27, 2019 at 16:27

answered Jun 27, 2019 at 14:32

Eliseo

58.9k4 gold badges39 silver badges82 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Eliseo Over a year ago

Has you see an error in console? (the strange is that a checkbox has value true/false -never ON, off or another)

Mandeep Singh Over a year ago

i was seeing error for dropdown but then i commented that code. code rendered all the checkboxes properly but problem was same. Moreover in Google Chrome nothing happens not even "on"

Eliseo Over a year ago

Updated my answer. The solution is , in ng-container check if type is checkbox or not, if is checkbox, directily write type="checkbox", else [type]="question.type"

Mandeep Singh Over a year ago

Great! thanks, It worked perfectly. but Can you explain why it was happening?. type was checkbox before as well.

Brackets Over a year ago

Life saver. How is there no issue on angular github?

|

Collectives™ on Stack Overflow

Checkbox value is not changing in reactive forms angular

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related