populate values in Form control from nested Form Array from JSON data

Question

FormArray The formObj has array of componentDetails Object which in turn has a nested array of component array.

   export class FormViewComponent implements OnInit {

    public callbackForm: FormGroup;

    formObj = {
        "componentDetails": [{
            "component": [{
                "value": "Choice 1"
            }, {
                "value": "Choice 2"
            }],
            "cpv": "",
            "label": "Description of Problem",
            "type": "radio",
            "mandatory": true
        }]
    };

    loadObservableForm() {
        this.formService.getData(this.id)
            .subscribe(
                (formObj) => {
                    this.formObj = formObj;
                    this.callbackForm = this._formBuild.group({
                        componentDetails: this._formBuild.array([])
                    });
                    this.addComponentDetails();
                },
                (err) => console.error(err),
                () => console.log('observable complete')
            );

    }

    addComponentDetails() {
        const control = <FormArray> this.callbackForm.controls.componentDetails;
        this.formObj.componentDetails.forEach(x => {
            control.push(this.addControl(x));
        });
    }

    addControl(x) {
        const group = this._formBuild.group({
            label: x.label,
            cpv: x.cpv,
            type: x.type,
            mandatory: x.mandatory,
            component: this._formBuild.array([this.addOptions(x)])
        });
        return group;
    }

    addOptions(z) {
        const control = < FormArray > z.component;
        z.component.forEach(y => {
            control.push(this.addOptionRow(y.value));
        });
    }

    addOptionRow(value) {
        return this._formBuild.group({
            value: value
        });
    }
}

Template HTML:

<form [formGroup]="callbackForm">
    <div>
        <div formArrayName="componentDetails">
            <div *ngFor="let question of callbackForm.controls.componentDetails.controls; let i = index;" [formGroupName]="i">
            <div class="row">
                <div class="col-md-12 panel-group panel-group--compressed">
                    <div class="panel panel--default">
                        <fieldset>
                            <div class="row" *ngIf="question.controls.type.value === 'radio'">
                                <div class="col-md-12">
                                    <p>{{ question.controls.label.value }}</p>
                                    <div formArrayName="component">
                                        <div *ngFor="let answer of question.controls.component.controls; let j = index" [formGroupName]="j">
                                        <label class="radio radio--alt radio--stacked">
                                        <input type="radio" name="radio-stacked">
                                        <span class="radio__input"></span>
                                        <span class="radio__label">{{ answer.value }}</span>
                                        </label>
                                    </div>
                                </div>
                            </div>
                    </div>
                    </fieldset>
                </div>
            </div>
        </div>
    </div>
    </div>
    </div>
</form>

Problem:

In the component template HTML, I cannot get the value for {{ answer.value }}. I tried with answer.controls.value.value and answer.controls.value. And nothing is working. question.controls.component.controls returns [Object Object]

Answer 1

You have trouble when calling addOptions inside the form array:

component: this._formBuild.array([this.addOptions(x)])

Place that below instead, so this will work. I omitted addOptions and addOptionRow from your code and instead applied the logic in addControl :

addControl(x) {
  const group = this._formBuild.group({
    label: x.label,
    cpv: x.cpv,
    type: x.type,
    mandatory: x.mandatory,
    component: this._formBuild.array([])
  });
  const ctrl = group.controls.component as FormArray;
  x.component.forEach(y => {
    ctrl.push(this._formBuild.group({
      value: y.value
    }))
  })
  return group;
}

and your template is otherwise correct, but to show the label do:

{{ answer.value.value }}

instead of

{{ answer.value }}

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