ng選擇的表達式不選擇時爲真

Question

當accommodation的索引爲0時，則將選定的attribute添加到選項中。我不確定我做錯了什麼。

以下是我與

<select formControlName="type" required> 
    <option value="{{ accommodation.id }}" *ngFor="let accommodation of ListAccommodationTypes; let i = index;" ng-selected="0 in i">{{ accommodation.name }}</option> 
</select> 

工作代碼這是它呈現在DOM

<select formcontrolname="type" required="" ng-reflect-name="type" class="ng-untouched ng-pristine ng-invalid"> 
    <!--template bindings={ 
     "ng-reflect-ng-for-of": "[object Object],[object Object],[object Object],[object Object],[object Object]" 
     }--> 
    <option ng-selected="0 in i" value="4" ng-reflect-value="4">Something 4</option> 
    <option ng-selected="0 in i" value="5" ng-reflect-value="5">Something 5</option> 
    <option ng-selected="0 in i" value="3" ng-reflect-value="3">Something 3</option> 
    <option ng-selected="0 in i" value="2" ng-reflect-value="2">Something 2</option> 
    <option ng-selected="0 in i" value="1" ng-reflect-value="1">Something 1</option> 
</select> 

我也曾嘗試

<select formControlName="type" required> 
    <option value="{{ accommodation.id }}" *ngFor="let accommodation of ListAccommodationTypes; let i = index;" ng-selected="i==0">{{ accommodation.name }}</option> 
</select> 

<select formControlName="type" required> 
    <option value="{{ accommodation.id }}" *ngFor="let accommodation of ListAccommodationTypes; let i = index;" ng-selected="{{i==0}}">{{ accommodation.name }}</option> 
</select> 

Answer 1

試試這個

<option *ngFor="let accommodation of ListAccommodationTypes; let i = index;" 
    [attr.selected]="i == 0 ? true : null"> 
    {{ accommodation.name }} 
</option>