Angular - select placeholder not showing - html

Question

is there any reason why this simple code won't work? I'm trying to have a placeholder on my select, but it simply shows as one of the other options in the list.
<div *ngFor="let d of formDatiRichiesta" class="form-row">
<select *ngIf="d.type=='select'"
class="form-control"
name="{{d.name}}"
[(ngModel)]="model[d.name]"
required>
<option selected disabled>{{d.placeholder}}</option>
<option *ngFor="let b of elencoBanche" value="{{b.id}}">{{b.denominazione}}</option>
</select>
</div>
I'm using angular4. Thanks.
--EDIT--
I found out that if I delete [(ngModel)]="model[d.name]" all works fine. Any hint?

Answer 1

You have to set the value of the <option> to the value of the model, because the <select> will use the value of the model as the default selection.
When the model is undefined at the beginning you can do it like this:
<option value="undefined">Please choose...</option>

Answer 2

That's how it is supposed to work. With the attributedisabled you can't choose it as an option.
But you could add the hidden attribute to also hide it:
<option value="" selected disabled hidden>{{d.placeholder}}</option>

Answer 3

<select formControlName="value" class="form-control"
style=" height: 40px">
<option [ngValue]="null" selected disabled hidden>Select</option>
<option>Save</option>
<option>Download</option>
</select>

Answer 4

Add this simply it will work.
<option value="" disabled>Select Category</option>
Or
<option [ngValue]="null">Select Category</option>