MyBatis報OgnlException: source is null for getProperty(null, “id”)異常

• 程式碼如下

    <sql id="where">

            <if test="requestStudent.id!=null and requestStudent.id!=''">
                and tb.id = #{requestStudent.id}
            </if>

            <if test="requestStudent.name!=null and requestStudent.name!=''"
 
>
                and tb.name = #{requestStudent.name}
            </if>
            <if test="requestStudent.age!=null and requestStudent.age!=''">
                and tb.age = #{requestStudent.age}
            </if>
            <if test="requestStudent.height!=null and requestStudent.height!=''"
 
>
                and tb.height = #{requestStudent.height}
            </if>
    </sql>

• 原因：

  • 以前的MyBatis可以像上面那樣直接”“判斷是否為null，現在不行了，要先判斷requestStudent是否為null才行，否則即使requestStudent不為null也會報source is null for getProperty(null, “id”)異常，即可能會有NPE空指標異常。

• 解決辦法：在外層加一個if判斷就行了

    <sql id="where"
 
>
        <if test="requestStudent!=null">
            <if test="requestStudent.id!=null and requestStudent.id!=''">
                and tb.id = #{requestStudent.id}
            </if>

            <if test="requestStudent.name!=null and requestStudent.name!=''">
                and tb.name = #{requestStudent.name}
            </if>
            <if test="requestStudent.age!=null and requestStudent.age!=''">
                and tb.age = #{requestStudent.age}
            </if>
            <if test="requestStudent.height!=null and requestStudent.height!=''">
                and tb.height = #{requestStudent.height}
            </if>
        </if>
    </sql>