source is null for getProperty(null, "fcityid")

进入页面 分页查询 直接报错

表单：

 <li><label>城市：</label>
                <form:select path="fcity.fcityid" class="input-medium" id="city" onchange="loadYsArea()">
                    <form:option value="">请选择</form:option>
                    <c:forEach items="${cities }" var="cityList">
                        <form:option value="${cityList.fcityid }">${cityList.fname }</form:option>
                    </c:forEach>

                </form:select>
            </li>

实体

 private YsCity fcity;      // 城市
    private YsArea farea;       // 区域
    private YsGarden fgarden;       // 社区
    get/set...

sql：

 <where>

            <if test="fhouseid != null and fhouseid != ''">
                AND a.fhouseid = #{fhouseid}
            </if>

            <if test="fcity.fcityid != null and fcity.fcityid != ''">
                AND a.fcity = #{fcity.fcityid}
            </if>
            <if test="farea.fareaid != null and farea.fareaid != ''">
                AND a.farea = #{farea.fareaid}
            </if>
            <if test="fgarden.fgardenid != null and fgarden.fgardenid != ''">
                AND a.fgarden = #{fgarden.fgardenid}
            </if>

错误信息

 2016-12-12 10:23:37,210 ERROR [500.jsp] - nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'fcity.fcityid != null and fcity.fcityid != '''. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "fcityid")
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'fcity.fcityid != null and fcity.fcityid != '''. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "fcityid")

不知道我贴的信息全不全 希望大神帮忙看看

最后的信息提示了，数据源为空，导致访问了空对象

同样的问题，一添加对状态的判断就报错，求解啊!!