Dynamically assigning drop down value

[rapropos]

Generally speaking (since you haven’t posted any code), the following structure is virtually always a mistake:

<div *ngFor="let foo of foos">
  <control [(ngModel)]="bar">
</div>

bar is an object property of the controller, so all the controls will be aliased. Ordinarily, you want this instead:

<div *ngFor="let foo of foos">
  <control [(ngModel)]="foo.bar">
</div>

This way each control has a dedicated backing property on each foo.