如何在Apigee X的XSL转换后移除XML声明标签

场景说明 #

用户发送包含对象数组的JSON payload，通过Apigee X的JSONtoXML和XSLT政策转换为SOAP服务所需XML格式，但转换后SOAP Body中出现<?xml version="1.0" encoding="UTF-8"?>声明标签，SOAP服务不接受该标签。

相关配置及输出 #

用户JSON Payload #

{"putPlcExamScore": {"Student": [{"ID": "Professor","Form": "S","GradePoints": "123"},{"ID": "Snape","Form": "7","GradePoints": "322"}]}}

JSONtoXML 政策配置 #

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<JSONToXML continueOnError="false" enabled="true" name="JX-JsontoXML">
    <DisplayName>JX-JsontoXML</DisplayName>
    <Properties/>
    <Options>
        <NullValue>NULL</NullValue>
        <NamespaceBlockName>#namespaces</NamespaceBlockName>
        <DefaultNamespaceNodeName>$default</DefaultNamespaceNodeName>
        <NamespaceSeparator>:</NamespaceSeparator>
        <TextNodeName>#text</TextNodeName>
        <AttributeBlockName>#attrs</AttributeBlockName>
        <AttributePrefix>@</AttributePrefix>
        <InvalidCharsReplacement>_</InvalidCharsReplacement>
        <ObjectRootElementName>Root</ObjectRootElementName>
        <ArrayRootElementName>Array</ArrayRootElementName>
        <ArrayItemElementName>Item</ArrayItemElementName>
    </Options>
    <OutputVariable>request</OutputVariable>
    <Source>request</Source>
</JSONToXML>

XSLT Transformation 政策配置 #

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<XSL continueOnError="false" enabled="true" name="XSLT-ConvertPayload">
    <DisplayName>XSLT-ConvertPayload</DisplayName>
    <Properties/>
    <Source>request</Source>
    <ResourceURL>xsl://PlacementScores.xsl</ResourceURL>
    <Parameters ignoreUnresolvedVariables="true"/>
    <OutputVariable>ps_modifiedpayload</OutputVariable>
</XSL>

XSL资源配置 #

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
    <xsl:strip-space elements="*"/>
    <xsl:template match="/">
        <put:putPlcExamScore xmlns:put="http://something.v1">
            <xsl:for-each-group select="//Student" group-by="ID">
            <xsl:for-each select="current-group()">
                <put:Student>
                    <put:ID>
                        <xsl:value-of select="ID"/>
                    </put:ID>
                    <put:Form>
                        <xsl:value-of select="Form"/>
                    </put:Form>
                    <put:GradePoints>
                        <xsl:value-of select="GradePoints"/>
                    </put:GradePoints>
                </put:Student>
            </xsl:for-each>
            </xsl:for-each-group>
        </put:putPlcExamScore>
    </xsl:template>
</xsl:stylesheet>

AssignMessage政策片段 #

<soapenv:Body>
    {ps_modifiedpayload}
</soapenv:Body>

问题输出（Trace中结果） #

<soapenv:Body>
  <?xml version="1.0" encoding="UTF-8"?>
  <put:putPlcExamScore xmlns:put="something.v1">
    <put:Student>
      <put:ID>Professor</put:ID>
      <put:Form>S</put:Form>
      <put:GradePoints>123</put:GradePoints>
    </put:Student>
    <put:Student>
      <put:ID>Snape</put:ID>
      <put:Form>7</put:Form>
      <put:GradePoints>322</put:GradePoints>
    </put:Student>
  </put:putPlcExamScore>
</soapenv:Body>

解决方案 #

方法1：修改XSL资源的输出配置（推荐） #

在XSL资源的<xsl:output>标签中添加omit-xml-declaration="yes"属性，直接让XSL转换时不生成XML声明标签。修改后的XSL资源如下：

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<!-- 添加omit-xml-declaration="yes"移除XML声明 -->
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" omit-xml-declaration="yes"/>
    <xsl:strip-space elements="*"/>
    <xsl:template match="/">
        <put:putPlcExamScore xmlns:put="http://something.v1">
            <xsl:for-each-group select="//Student" group-by="ID">
            <xsl:for-each select="current-group()">
                <put:Student>
                    <put:ID>
                        <xsl:value-of select="ID"/>
                    </put:ID>
                    <put:Form>
                        <xsl:value-of select="Form"/>
                    </put:Form>
                    <put:GradePoints>
                        <xsl:value-of select="GradePoints"/>
                    </put:GradePoints>
                </put:Student>
            </xsl:for-each>
            </xsl:for-each-group>
        </put:putPlcExamScore>
    </xsl:template>
</xsl:stylesheet>

方法2：使用Apigee JavaScript政策移除声明标签 #

如果无法修改XSL资源，可以添加一个JavaScript政策，对ps_modifiedpayload变量进行字符串替换，移除XML声明：

var payload = context.getVariable('ps_modifiedpayload');
// 移除XML声明标签
var cleanedPayload = payload.replace(/<\?xml[^>]+>/g, '');
context.setVariable('ps_modifiedpayload', cleanedPayload);

然后在AssignMessage政策之前执行这个JavaScript政策即可。

内容的提问来源于stack exchange，提问作者Kranthi Bandaru