错误：filter：notarray即使语法正确，也不是数组

Question

我正在尝试调用API但是在加载页面时出现Not a array错误。来自JSON的数据没有显示出来。

这是代码中有问题的部分：

<div class="row" style="margin-top: 20px">
   <div class="col-sm-6">
     <h4>TESTCASES</h4>
       <div ng-repeat="school in schools | filter: {selected: '!true'} track by $index">
         <span class="list-group-item" ng-click="school.status =!school.status" style="background-color:rgba(115,158,226,1);">{{school.name}}</span>
         <span class="list-group-item" ng-if="school.status" ng-repeat="subSchool in school.sub | filter: {selected: '!true'} track by $index" ng-click="select(subSchool)" tooltip= '{{subSchool.name}}, Run Time: {{subSchool.runTime}}'>{{subSchool.name}}</span>
        </div>
       </div>
       <div class="col-sm-6">
          <h4>TEST PLAN</h4>
              <div class="list-group list-select">
                <span class="list-group-item" ng-repeat="school in selected track by $index" ng-click="deselect(school)">{{school.name}}</i></span>
              </div>
        </div>
       </div>