如何订阅两个输入字段并使它们在 Angular 2 中相互切换？

Question

I have a checkbox and input field,

Case One :

• If the input field isn't empty checkbox will be disabled.
• If the input field is empty checkbox will be enabled.

Case Two :

• If the checkbox checked, Input field will be disabled.
• f the checkbox isn't checked, Input field will be enabled.

here is angular html part;

 <form [formGroup]="testForm"> <div> <label for="veggieMustard">show Text</label> <input formControlName="showTextInput" id="showText" type="text" /> </div> <div> <input formControlName="showCheckbox" id="showCheckBox" type="checkbox" /> <label for="showCheckBox">show</label> </div> </form>

Angular Controller:

 import { Component, OnInit } from '@angular/core'; import { FormGroup, FormBuilder, FormControl, } from '@angular/forms'; @Component({ selector: 'order-sheet', templateUrl: './test-form.component.html', styleUrls: ['./test-form.component.css'], }) export class TestController implements OnInit { testForm: FormGroup; constructor(private formBuilder: FormBuilder) { this.buildForm(); } ngOnInit() { this.subscribeToShowTextInput(); this.subscribeToShowCheckBox(); } buildForm(): void { this.testForm = this.formBuilder.group( { showTextInput: this.formBuilder.control(null), showCheckbox: this.formBuilder.control(null), } // To Disable or Enable the Checkbox depeneds on the input field status private subscribeToShowTextInput(): void { const showCheckbox = this.orderSheetForm.controls['showCheckbox']; this.orderSheetForm.controls['showTextInput'].valueChanges.subscribe( (value) => { if (value) { showCheckbox.disable(); } else { showCheckbox.enable(); } console.log(value); } ); } // To Disable or Enable the Input field depeneds on the Checkbox status private subscribeToShowCheckBox(): void { const showTextInput = this.orderSheetForm.controls['showTextInput']; this.orderSheetForm.controls['showCheckbox'].valueChanges.subscribe( (value) => { if (value) { showTextInput.setValue(''); showTextInput.disable(); } else { showTextInput.enable(); } console.log(value); } ); }}

I am getting this Error ERROR RangeError: Maximum call stack size exceeded Which happened because the subscription is always updating each other which gets me into infinite loop, if i disable one of the subscription it works fine,

Do anyone have any good idea to deal with such situation ?

I'm appreciating any suggestions, directing to documentations or article, because i spend days searching, but i did not find something useful to my situation.

Thank you in advance.

Answer 1

You should pass in the emitEvent: false option when disabling and enabling the controls.

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormControl } from '@angular/forms';

@Component({
  selector: 'form',
  templateUrl: 'form.component.html',
  styles: [],
})
export class FormComponent {
  form = this.fb.group({
    showCheckbox: new FormControl(),
    showTextInput: new FormControl(),
  });

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.subscribeToShowTextInput();
    this.subscribeToShowCheckBox();
  }

  private subscribeToShowTextInput(): void {
    this.showTextInput.valueChanges.subscribe((value) => {
      if (value) {
        this.showCheckbox.disable({ emitEvent: false });
      } else {
        this.showCheckbox.enable({ emitEvent: false });
      }
    });
  }

  private subscribeToShowCheckBox(): void {
    this.showCheckbox.valueChanges.subscribe((value) => {
      if (value) {
        this.showTextInput.setValue('');
        this.showTextInput.disable({ emitEvent: false });
      } else {
        this.showTextInput.enable({ emitEvent: false });
      }
    });
  }

  get showCheckbox() {
    return this.form.get('showCheckbox');
  }

  get showTextInput() {
    return this.form.get('showTextInput');
  }
}