未终止的属性选择器

Question

我尝试使用@each sass函数，但是我总是收到错误Unterminated attribute selector for track。我不知道我的代码在哪里。

HTML

<ion-list>
      <ion-item-sliding [attr.track]="green" >
        <ion-item>
          Item
        </ion-item>
        <ion-item-options side="left">


          <button ion-button (click)="favorite(item)">Favorite</button>
          <button ion-button color="danger" (click)="share(item)">Share</button>
        </ion-item-options>

        <ion-item-options side="right">
          <button ion-button (click)="unread(item)">Unread</button>
        </ion-item-options>
      </ion-item-sliding>
    </ion-list>

SASS CSS密码

@each $track, $value in auxiliary-categories() {
  ion-item-sliding [track=#{$track}] ion-label {
    border-left: 5px solid $value;
    padding-left: 10px;
  }
 }


 $categories: (
    ionic: color($colors, primary),
    angular: #AC282B,
    communication: #8E8D93,
    red: #FE4C52,
    yellow: #FED035,
    green: #69BB7B,
    blau: #3BC7C4,
 );

 @function auxiliary-categories() {
     @return map-remove($categories);
 }