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Pre-filling input submitted to a `FormGroup` - Angular2

I am using Angular2 - Reactive Forms. Everything works fine as long as I don't want to show the pre-filled value in one of the form fields.

Scenario: There are multiple buttons on the page and each button opens a form with fields like

  • Name
  • Email
  • Message
  • Product code → The value for this must be pre-filled according to the product code from the service.

Script Failure: Input Product Code value is null.

TS code:

import { FormGroup, FormBuilder, Validators } from '@angular/forms';
queryForm: FormGroup;
constructor(private _productService: ProductService, fb: FormBuilder) {
    this.queryForm = fb.group({
        'name': [null, Validators.compose([Validators.required, Validators.minLength(5)])],
        'email': [
            null, [Validators.required, Validators.email]
        ],
        'message': [null,Validators.compose([Validators.required, Validators.minLength(5)])],
        'pcode': [
            null
        ],
    })
}

HTML form:

<div *ngFor="let item of product">
<form action="#" [formGroup]="queryForm" 
 (ngSubmit)="submitForm(queryForm.value)" method="post" 
  novalidate="" class="text-left note" id="f_{{item.productId}}">
    [ .... rest of the fields ...]
    <div class="form-group hidden">
          <input type="hidden " class="form-control " id="pcode " name="pcode" 
        formControlName="pcode" [value]="item.productCode" />
     </div>
     <div class="form-group">
           <button type="submit" class="btn1" [disabled]="!queryForm.valid">Submit</button>
      </div>
</form>
</div>

How can I achieve this?

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1 answer


UPDATE: As it turned out, you need formArray

one instead formControl

. So declare that when you create the form:

this.queryForm = this.fb.group({
  arrayOfData: this.fb.array([]) // name a proper name to array
})

You can use setValue

or patchValue

when you got your data where you iterate over the response and correct the values ​​in your form array. Call the patchValues

-method in your callback (subscribe).

patchValues() {
  const control = <FormArray>this.queryForm.controls.arrayOfData;
  this.items.forEach(x => {
    control.push(this.patchValue(x.first_name, x.pcode))
  })
}

patchValue(name, code) {
  return this.fb.group({
    name: [name],
    pcode: [code]
  })    
}

In your template iterate the formarray and also don't forget to include the formgroupname (which is the index):

<div formArrayName="arrayOfData">
  <div *ngFor="let code of queryForm.controls.arrayOfData.controls; let i = index">
    <div formGroupName="{{i}}">
      <label>Name: </label>
      <input formControlName="name" /><br>
      <label>Product Code: </label>
      <input formControlName="pcode" /><br>
    </div>
  </div>
</div>

Demo



Original answer:

You should always set the form values ​​in the component and not in the template. You can use patchValue

or setValue

when you got the value from the service ... so you can do this, for example, inside a callback (subscribe):

this.myService.getSomeData()
  .subscribe(data => {
     this.item = data;
     this.queryForm.patchValue({pcode: this.item.productCode})
  });

Then you don't need to use it [value]="item.productCode"

in your form, this value is set instead of the form control.

Demo

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