复合MEL语句存在问题

Question

我需要从配置文件中读取值，并且一直遇到嵌入式MEL语句的问题；我追逐多个死胡同，没有想法。我使用一个会话变量将其提取为一个相当简单的示例。

谢谢,

• 完成

以下代码在以下情况下失败：

消息:错误:丢失左节点

[近：{.message.payload.contains(#[sessionVars'valueToMatch']) .}

    <set-session-variable variableName="valueToMatch" value="Now we are engaged in a great civil war" />        
    <choice doc:name="Choice">
        <when expression="#[message.payload.contains(#[sessionVars['valueToMatch']])]">
            <set-session-variable variableName="success" value="true" />        
        </when>
        <otherwise>
            <set-session-variable variableName="success" value="false" />       
        </otherwise>
    </choice>

然而，以下代码起作用：

    <choice doc:name="Choice">
        <when expression="#[message.payload.contains('Now we are engaged in a great civil war')]">
            <set-session-variable variableName="success" value="true" />        
        </when>
        <otherwise>
            <set-session-variable variableName="success" value="false" />       
        </otherwise>
    </choice>

Answer 1

我的猜测是，问题在于您要在表达式中放置一个分隔的表达式，尝试如下：

"#[message.payload.contains(sessionVars['valueToMatch'])]"

而不是这个

"#[message.payload.contains(#[sessionVars['valueToMatch']])]"

Answer 2

试试这个#[message.payload contains valueToMatch] ..。它将完美而简单地工作：-

<set-session-variable variableName="valueToMatch" value="Now we are engaged in a great civil war" />        
    <choice doc:name="Choice">
        <when expression="#[message.payload contains valueToMatch]">
            <set-session-variable variableName="success" value="true" />        
        </when>
        <otherwise>
            <set-session-variable variableName="success" value="false" />       
        </otherwise>
    </choice>