Controller部分：

    public function getFollowCategory()
    {
        $type = $this->request->param('type');
        $category = model('CourseCategory');

        $list = [];
        switch ($type) {
            case 1: //专项练习
                $list = collection($category->field('id,name')->where('pid','in',[14,15])->select())->toArray();

                return $list;
            case 2: //随堂练习
                $course = model('Course');
                $list = collection($course->field('id,title as name')->select())->toArray();

                return $list;
            case 3: //模拟试卷
                $list = $category->where('id','in',[14,15])->select();
                return $list;

        }

    }

view部分：

    <div class="form-group">
        <label class="control-label col-xs-12 col-sm-2">{:__('exam_type')}:</label>
        <div class="col-xs-12 col-sm-8">
<!--            {:build_radios('row[exam_type]', ['normal'=>__('Normal'), 'hidden'=>__('Hidden')])}-->
            <div class="radio">
                {foreach name="examTypeList" item="vo"}
                <label for="row[exam_type]-{$key}"><input id="row[exam_type]-{$key}" name="row[exam_type]" type="radio" value="{$key}" {in name="key" value="1"}checked{/in} /> {$vo}</label>
                {/foreach}
            </div>
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-xs-12 col-sm-2">{:__('Category_id')}:</label>
        <div class="col-xs-12 col-sm-8">
            <select  id="c-category_id" class="form-control selectpicker" name="row[category_id]">
                <option value="0" id="category_id">请选择</option>
            </select>
        </div>
    </div>

js部分：

api: {
            bindevent: function () {
                Form.api.bindevent($("form[role=form]"));

                $("input:radio[name='row[exam_type]']").change( function() {//单击时方法
                    $.post('answer_paper/getFollowCategory',
                        {
                            'type':$(this).val()
                        },
                        function (data) {
                            $('#c-category_id').html("");
                            for(var i in data){
                                $('#c-category_id').append('<option value="'+data[i]['id']+'">'+data[i]['name']+'</option>')
                            }
                            $('#c-category_id').selectpicker('refresh');
                        }
                    );
                });

                $('.sender').on('changed.bs.select', function() {//单击时方法
                    // console.log('agja');
                    var $type = $(this).val();
                    console.log($('.sender').selectpicker('val'));

                    $.post('answer_paper/getFollowUser',
                        {
                            'type':$type
                        },
                        function (data) {
                            $('#c-external_userid').html("");
                            for(var i in data){
                                $('#c-external_userid').append('<option value="'+data[i]['id']+'">'+data[i]['name']+'</option>')
                            }
                            $('select').selectpicker('refresh');
                        }
                    );
                });


            }

        }
    };