Nested Forms in angular2

Question

How to create form with nesting fields, i know about formArray in angular2 RC but am bit confused how to use it correctly ? let suppose i have an form like this

// Main Form with formArray named as `global_modifier`
this.myForm = this._fb.group({
  .......
  name: ['', []],
  global_modifier: this._fb.array([
    this.initGlobalModifiers()
  ])
  ....
});


removeModifier(i: number) {
  const control = <FormArray>this.myForm.controls['global_modifier'];
  control.removeAt(i);
}

addModifier() {
  const control = <FormArray>this.myForm.controls['global_modifier'];
  control.push(this.initGlobalModifiers());
}

/*global_modifier function having nested fields named `items` .....*/
initGlobalModifiers() {
  return this._fb.group({
  .....
    modifier_title: ['', []],
    items: this._fb.array([
      this.initItems()
    ])
    .........
  });
}


removeItem(i: number) {
  const control = <FormArray>this.myForm.controls['items'];
  control.removeAt(i);
}

addItem() {
  const control = <FormArray>this.myForm.controls['items'];
  control.push(this.initItems());
}

// items intilization
initItems() {
  return this._fb.group({
    item_title: ['', []],
    item_price: ['', []]
  });
}

now i am confused how to use this form in the html ??

i am trying this but did't work as expected..

<form [formGroup]="myForm" novalidate>
  <input type="text" placeholder="name" formControlName="name" maxlength="50">
  <div formArrayName="global_modifier" *ngFor="let cont of myForm.controls.global_modifier.controls; let i=index, let fst=first">
    <div [formGroupName]="i">
      <input type="text" placeholder="modifier_title" formControlName="modifier_title" maxlength="50">
      <button *ngIf="fst" [ngClass]="{'inputAddButton ':fst}" (click)="addModifier(i)" type="button">
        <i class="fa fa-plus fa-white" aria-hidden="true"></i>
      </button>
      <button *ngIf="!fst" [ngClass]="{'inputDeleteButton ':!fst}" (click)="removeModifier(i)">
        <i class="fa fa-trash-o fa-white" aria-hidden="true"></i>
      </button>

      <!--block For form mlutiple entrys-------------------->
      <div formArrayName="items">
        <div *ngFor="let items of cont.items; let item_index=index, let fst=first">
          <div [formGroupName]="i">
            <div style="margin-bottom:10px">
                     ............... NOTHING dISPLAY HERE ???
            </div>
          </div>
        </div>
      </div>
      <!--block For form mlutiple entrys---=------------>
      <br>
    </div>
  </div>
</form>

whats the error in my code ? or anyone having working example of nested forms in angular2 ?

Answer 1

Check this example that worked for me until rc4 (didn't check in newer versions):

form markup

  ngOnInit() {
    this.myForm = this.formBuilder.group({
    'loginCredentials': this.formBuilder.group({
    'login': ['', Validators.required],
    'email': ['',  [Validators.required, customValidator]],
    'password': ['',  Validators.required]
   }),
    'hobbies': this.formBuilder.array([
      this.formBuilder.group({
        'hobby': ['', Validators.required]
      })
    ])
  });
}

removeHobby(index: number){
    (<FormArray>this.myForm.find('hobbies')).removeAt(index);
  }

  onAddHobby() {
    (<FormArray>this.myForm.find('hobbies')).push(new FormGroup({
      'hobby': new FormControl('', Validators.required)
    }))
  }

html markup

<h3>Register page</h3>
<form [formGroup]="myForm" (ngSubmit)="onSubmit()">
  <div formGroupName="loginCredentials">
    <div class="form-group">
      <div>
        <label for="login">Login</label>
        <input  id="login" type="text" class="form-control" formControlName="login">
  </div>
  <div>
    <label for="email">Email</label>
    <input  id="email" type="text" class="form-control"  formControlName="email">
  </div>
  <div>
    <label for="password">Password</label>
    <input  id="password" type="text" class="form-control"  formControlName="password">
      </div>
    </div>
  </div>
  <div class="row" >
    <div  formGroupName="hobbies">
      <div class="form-group">
        <label>Hobbies array:</label>
        <div  *ngFor="let hobby of myForm.find('hobbies').controls; let i = index">
          <div formGroupName="{{i}}">
            <input id="hobby_{{i}}" type="text" class="form-control"  formControlName="hobby">
            <button *ngIf="myForm.find('hobbies').length > 1" (click)="removeHobby(i)">x</button>
          </div>
        </div>
        <button (click)="onAddHobby()">Add hobby</button>
      </div>
    </div>
  </div>
  <button type="submit" [disabled]="!myForm.valid">Submit</button>
</form>

Remarks

this.myForm = this.formBuilder.group

creates a form object with user's configuration and assigns it to this.myForm variable.

---

'loginCredentials': this.formBuilder.group

method creates a group of controls which consist of a formControlName eg. login and value ['', Validators.required], where the first parameter is the initial value of the form input and the secons is a validator or an array of validators as in 'email': ['', [Validators.required, customValidator]],.

---

'hobbies': this.formBuilder.array

Creates an array of groups where the index of the group is formGroupName in the array and is accessed like :

<div *ngFor="let hobby of myForm.find('hobbies').controls; let i = index">
<div formGroupName="{{i}}">...</div>
</div>

---

onAddHobby() {
(<FormArray>this.myForm.find('hobbies')).push(new FormGroup({
'hobby': new FormControl('', Validators.required)
}))
}

this sample method adds new formGroup to the array. Currently accessing requires specifing the type of control we want to access, in this example this type is : <FormArray>

---

removeHobby(index: number){
(<FormArray>this.myForm.find('hobbies')).removeAt(index);
}

same rules as above apply to removing a specific form control from the array