layui怎么设置select默认选中，修改回显

后端取出的值

      <div class="layui-form-item" style="position: relative;z-index: 10;">
            <label class="layui-form-label">文章分类</label>
            <div class="layui-input-block" lay-filter="selFilter">
                <select name="category.categoryId" id="category-Id" lay-filter="selFilter" style="width:100%;height:40px">
                    <#list categories as c>
                        <option value="${c.categoryId}" > ${c.categoryName} </option>
                    </#list>
                </select>
            </div>
        </div>

由于修改时需要回显
在获取单个信息时写ajax修改默认选中

       var form = layui.form
                $ = layui.$;
                $('#category-Id').find("option[value="+data.category.categoryId+"]").attr("selected",true);
                form.render('select');

完整的方法

  function getArticle(articleId){
        $.ajax({
            url:'/get_article?articleId='+articleId,
            type:'post',
            dataType: 'json',
            success:function (data){

                $('#title').val(data.title);
                $('#summary').val(data.summary);
                $('#imgView').attr("class","");
                editor.txt.html(data.content);
                $('#category-Id2').selected;
                $('#picture').attr("src", "http://manage.knews.com/images/"+data.image);

                var form = layui.form
                $ = layui.$;
                $('#category-Id').find("option[value="+data.category.categoryId+"]").attr("selected",true);
                form.render('select');

            }
    })