TP5 designated lecturer on the next page article

Controller code 

        
            [($cidKey +1)] : false;
        $nexCourseId = array_key_exists($cidKey-1, $courseIds) ? $courseIds[($cidKey -1)] : false;

        $this->assign([
            'course' => $course,
            'preCourseId' => $preCourseId,
            'nexCourseId' => $nexCourseId,
            'model' => new CourseModel
        ]);

 Template code

{{if condition="$preCourseId !== false"}}
<div>
     <span class="font-bold">上一篇：</span><a href="{{:url('index/teacher/cindex', ['cid' => $preCourseId])}}">{{$model->get($preCourseId)['title']}}</a>
</div>
{{/if}}
{{if condition="$nexCourseId !== false"}}
<div>
    <span class="font-bold">下一篇：</span><a href="{{:url('index/teacher/cindex', ['cid' => $nexCourseId])}}">{{$model->get($nexCourseId)['title']}}</a>
</div>
{{/if}}