reader/pages/user/mycollection/mycollection.wxml

<view class='my-collection'>
  <view class='collection-article' wx:for="{{ collection_data }}" wx:key="{{ index }}" bindtap='toClass' data-targetCode="{{item.targetCode}}" data-title='{{ item.title }}'>
    <view class='video-preview'>
      <image src='{{ item.iconImg }}'></image>
    </view>
    <view class='content-title'>
      {{ item.title }}
    </view>
    <view class='content-detail'>
      <view class='left'>{{ item.summary }}</view>
    </view> 
  </view>
   <myPlacerholder line1="{{line1}}" line2="{{line2}}" wx:if="{{collection_data.length <= 0}}" />  
</view>