复杂Mule XPath表达式引发异常

Question

我正试图在Mule中运行下面的XPath表达式。它让我犯了一个又一个错误。有人能帮我纠正这些Mule XPath表达式吗：

 <xm:namespace-manager includeConfigNamespaces="true">
      <xm:namespace prefix="acord" uri="ACORD.org/Standards/Life/2" />
      <xm:namespace prefix="soap" uri="schemas.xmlsoap.org/soap/envelope/" />
    </xm:namespace-manager>
    <set-variable variableName="pwaHolding"
         value="#[xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc = '37']/@OriginatingObjectID').value" />
    <set-variable variableName="pwaPolNumber"
         value="#[xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Holding[@id=$pwaHolding]/acord:Policy/acord:PolNumber').text]" />

当我尝试执行上面的XPATH表达式时，出现以下异常：

    Message  :Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String
    Code                  : MULE_ERROR--2
    --------------------------------------------------------------------------------
    Exception stack is:
    1. [Error: unexpected token: 37]
    [Near : {... @tc == '37']/@OriginatingObjec ....}]
                                  ^
    [Line: 1, Column: 96] (org.
mvel2.CompileException)
org.mvel2.compiler.ExpressionCompiler:247 (null)
2. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException)
org.mule.el.mvel.MVELExpressionLanguage:211 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/expression/ExpressionRuntimeException.html)
3. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String (org.mule.api.transformer.TransformerMessagingException)
org.mule.transformer.AbstractTransformer:123 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/transformer/TransformerMessagingException.html)
--------------------------------------------------------------------------------
Root Exception stack trace:
[Error: unexpected token: 37]
[Near : {... @tc == '37']/@OriginatingObjec ....}]                              ^
[Line: 1, Column: 96]
at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:247)
at org.mvel2.util.ParseTools.subCompileExpression(ParseTools.java:1944)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:862) 
+ 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)

你好，大卫，

即使用"替换了'，我仍然会出现以下错误：

消息：执行表达式"xpath（'//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc=='37']/@OriginatingObjectID'）.value"失败。（org.mule.api.exexpression.ExpressionRuntimeException）。消息负载的类型为：String代码：MULE_ERROR--2--------------------------------------------------------------------------------异常堆栈为：1.[错误：意外令牌：37][附近：｛…@tc=='37']/@OriginangObjec……｝]^[行：1，列：96]（org.mvel2.CompileException）org.mvel2.compiler.ExpressionCompiler:247（null）2.执行表达式"xpath（'//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc=='37']/@OriginatingObjectID'）.value"失败。（org.mule.api.expression.ExpressionRuntimeException）org.mule.el.mwel.mvel表达语言：211(http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/expression/ExpressionRuntimeException.html)3.执行表达式"xpath（'//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc=='37']/@OriginatingObjectID'）.value"失败。（org.mule.api.exexpression.ExpressionRuntimeException）。消息负载的类型为：String（org.mule.api.transformer.TransformerMessagingException）org.mule.transformer.AbstractTransformer:123(http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/transformer/TransformerMessagingException.html)

我的第二个XPATH表达式也有问题，它也失败了。也请帮我绕过这个

Answer 1

错误来自于在由'分隔的字符串中使用'，这是不起作用的。例如，在以下表达式中，问题围绕'37':

value="#[xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc = '37']/@OriginatingObjectID').value" />

另一个问题是MEL表达式末尾缺少一个闭合]。

试用：

value="#[xpath("//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc = '37']/@OriginatingObjectID").value" />

看看您的第二个XPath，我看到了[@id=$pwaHolding]。我假设此时您正在尝试使用由第一个XPath提取的pwaHolding流变量。这将不起作用，因为MVEL没有字符串插值。您需要使用串联，顺便说一句，不要忘记对@id的值进行单引号比较：

[@id‌='" + pwaHolding + "']