oa办公管理系统部门Mapper接口${current_department.departmentName}出错

问题遇到的现象和发生背景

06-Jan-2022 10:14:52.541 严重 [http-nio-80-exec-7] freemarker.log.JDK14LoggerFactory$JDK14Logger.error 

Expression current_department is undefined on line 25, column 49 in index.ftl.
The problematic instruction:
----------
==> ${current_department.departmentName} [on line 25, column 47 in index.ftl]
----------

Java backtrace for programmers:
----------
    freemarker.core.InvalidReferenceException: Expression current_department is undefined on line 25, column 49 in index.ftl.
        at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:124)
        at freemarker.core.TemplateObject.invalidTypeException(TemplateObject.java:134)
        at freemarker.core.Dot._getAsTemplateModel(Dot.java:78)
        at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
        at freemarker.core.Expression.getStringValue(Expression.java:93)
        at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.MixedContent.accept(MixedContent.java:92)
        at freemarker.core.Environment.visit(Environment.java:196)
        at freemarker.core.Environment.process(Environment.java:176)
        at freemarker.template.Template.process(Template.java:232)
        at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:427)
        at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:366)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:655)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712)
        at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:462)
        at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:388)
        at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:316)
        at com.imooc.oa.controller.IndexServlet.doGet(IndexServlet.java:39)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:655)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)

问题相关代码，请勿粘贴截图

```html
  <a href="javascript:void(0)">
                    <!--图标-->
                    <span class="layui-icon layui-icon-user" style="font-size: 20px">
                    </span>
                    <!--用户信息-->
                    ${current_employee.name} [${current_department.departmentName}-${current_employee.title}]
                </a>

```html
<mapper namespace="com.imooc.oa.dao.DepartmentDao">
    <select id="selectById" parameterType="Long" resultType="com.imooc.oa.entity.Department">
        select * from adm_department where department_id = #{value}
    </select>
</mapper>

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

输入用户后显示对应部门

Expression current_department is undefined
是current_employee吧

${current_employee.name} [${current_department.departmentName}-${current_employee.title}]
改为
${current_employee.name} [${current_employee.departmentName}-${current_employee.title}]

找不到current_department变量，返回的部门对象是不是封装在current_employee里面呢？

current_department.departmentName
改为
current_employee.current_department.departmentName
试试

current_department 你这个变量没搞 你看看全局变量里有没有这个