当formcontrol在select标记上时，selected属性不起作用

Question

预期行为

当所选值设置为在选择下拉列表中设置该选项时

HTML代码：

<select id="products" class="form-control new-select padding" formControlName="featured_product">
 <option>Please Select</option> 
<option *ngFor="let p of products" [ngValue]="p" [attr.selected]="p.ProductId == product.ProductId ? '': null" >{{p.ProductName}}</option>
 </select>

Answer 1

 <select id="products" class="form-control new-select padding" formControlName="featured_product">
   <option>Please Select</option> 
   <option *ngFor="let p of products" [value]="p" [attr.selected]="p.ProductId == product.ProductId ? '': null" >{{p.ProductName}}</option>
 </select>

我已经尝试过这段代码并且工作正常。

products = [{ProductId: 1, ProductName : 'a'},
   {ProductId: 2, ProductName : 'ab'},
   {ProductId: 3, ProductName : 'abc'},
   {ProductId: 4, ProductName : 'abcd'} ];

product =  {ProductId: 2, ProductName : 'ab'};