Unexpectedly, the current value is not displayed in the Angular2 dropdown select element that contains multiple group options

Within my Angular2 application, I have a dropdown element with 3 different option groups. Here is how it's structured:

<select formControlName="reasonCode" id="reasonCode" class="form-control">
      <option value="" [ngValue]="null"></option>
      <option *ngFor="let reason of otherLeavingReasons" [ngValue]="reason.longName">
        {{reason.longValue}}
      </option>
      <optgroup label="Managed">
        <option *ngFor="let reason of managedLeavingReasons"[ngValue]="reason.longName">
          {{reason.longValue}}
        </option>
      </optgroup>
      <optgroup label="Unmanaged">
        <option *ngFor="let reason of unmanagedLeavingReasons"[ngValue]="reason.longName">
          {{reason.longValue}}
        </option>
      </optgroup>
    </select>

To position the element based on its current value, I added the following code to each option group:

[selected]="reason.longValue == eventForm.controls['reasonCode'].value.longValue"

The issue I'm facing is that this approach doesn't seem to be working as expected. My suspicion is that the problem lies in having 3 option groups. Is there an alternative method to achieve this functionality or perhaps a different component that can handle multiple option groups within a single group?

Answer №1

If you are utilizing ReactiveModule forms, there is no need to manually add the [selected] attribute to each option. Simply set the model value and Angular will take care of updating the UI for you.

To implement this in your code, place the following snippet inside your component:

this.form.controls['reasonCode'].patchValue("myvalue");

Answer №2

After some trial and error, I was able to sort out the issue. It seems that using [ngValue] and [selected] together is causing a problem in my app. Once I removed [ngValue], the selection started working properly. Although this may not be the final or recommended solution, it worked in this specific case. Here is the modified code that resolved the issue:

<select formControlName="reasonCode" id="reasonCode" class="form-control" (change)="markTouched('reasonCode')">
      <option value=""></option>
      <option *ngFor="let reason of otherLeavingReasons" [selected]="reason.longValue == eventForm.controls['reasonCode'].value">
        {{reason.longValue}}
      </option>
      <optgroup label="Managed">
        <option *ngFor="let reason of managedLeavingReasons" [selected]="reason.longValue == eventForm.controls['reasonCode'].value">
          {{reason.longValue}}
        </option>
      </optgroup>
      <optgroup label="Unmanaged">
        <option *ngFor="let reason of unmanagedLeavingReasons" [selected]="reason.longValue == eventForm.controls['reasonCode'].value">
          {{reason.longValue}}
        </option>
      </optgroup>
    </select>

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