Java 获得；空"；尝试访问mybatis mapper xml中的对象变量时 在输入getEventsByTypeAndProductEvaluation之前，请确保有用于evaluation和eventType的toString方法，并在此处显示它们。

获得；空"；尝试访问mybatis mapper xml中的对象变量时

---

在输入getEventsByTypeAndProductEvaluation之前，请确保有用于evaluation和eventType的toString方法，并在此处显示它们。是否已验证调用接口方法getEventsByTypeAndProductEvaluation（）时没有传入null参数？您的对象可能不是空的，但ID是空的！！！

public interface RawProductEvaluationEventDao 
{

public List<ProductEvaluationEvent> getEventsByTypeAndProductEvaluation(
        @Param("evaluation") ProductEvaluation evaluation,
        @Param("eventType") EventType eventType);
}

<select id="getEventsByTypeAndProductEvaluation" resultType="ProductEvaluationEvent">
    SELECT
    id, 
    productEvaluationFk, 
    eventTimestamp,
    receiptEventTypeFk,
    isStartEvent,
    isSuccess,
    supplementalEventText,
    exceptionStackTraceText
    FROM
    productEvaluationEvent
    WHERE productEvaluationFk = #{evaluation.id}
    AND receiptEventTypeFk = #{eventType.id}
</select>

14:47:39 DEBUG c.r.w.p.d.r.R.getEventsByTypeAndProductEvaluation - ==>  Preparing: SELECT id, productEvaluationFk, eventTimestamp, receiptEventTypeFk, isStartEvent, isSuccess, supplementalEventText, exceptionStackTraceText FROM productEvaluationEvent WHERE productEvaluationFk = ? AND receiptEventTypeFk = ? 
14:47:39 DEBUG c.r.w.p.d.r.R.getEventsByTypeAndProductEvaluation - ==>   Parameters: null, null