仅当包装在事务中时，用于数据库查询的NullPayload

Question

我有一个流，当包装在多事务中时，它总是返回NullPayload。当我删除多事务标记时，我得到了预期的结果。为什么会这样呢？以下是代码片段

<flow name="successful-flow" processingStrategy="synchronous">
    <vm:inbound-endpoint exchange-pattern="request-response" path="order-process.in" doc:name="VM"/>
    <ee:multi-transactional action="ALWAYS_BEGIN" doc:name="Transactional" >
        <foreach collection="#[message.payload]" doc:name="For Each"
        rootMessageVariableName="Original">
            <jms:outbound-endpoint queue="orders.queue"
            connector-ref="jmsConnector" doc:name="JMS - Send to Order Processing Queue">
            <jms:transaction action="JOIN_IF_POSSIBLE"/>
        </jms:outbound-endpoint>
        </foreach>
    <db:insert config-ref="ORDER_DB" doc:name="Save Orders" >
        <db:parameterized-query><![CDATA[insert into orders(PRODUCT_ID,LINE_ITEM_CODE,PRICE,LST_UPDT_TMSP) VALUES('XXT665,'TP',20.99,'09/09/2010')]]></db:parameterized-query>
    </db:insert>
    </ee:multi-transactional>
    <response>
        <db:select config-ref="ORDER_DB" doc:name="Database" transactionalAction="ALWAYS_JOIN">
            <db:parameterized-query><![CDATA[select count(*) from orders]]></db:parameterized-query>
        </db:select>
    </response>
    <catch-exception-strategy doc:name="Order Processing Exception">
        <logger
            message="Error  during  flow - #[message] :: Exception::= #  [exception.summaryMessage]"
            level="ERROR" doc:name="Logger" />
    </catch-exception-strategy>
</flow>

Answer 1

我的错，之前的事务将不会完成和提交。select查询的默认transactionalAction是JOIN_IF_POSSIBLE，这意味着我将在插入和提交数据之前读取数据。简单的修复方法如下：

<response>
    <db:select config-ref="ORDER_DB" doc:name="Database" transactionalAction="NOT_SUPPORTED">
        <db:parameterized-query><![CDATA[select count(*) from orders]]></db:parameterized-query>
    </db:select>
</response>