如何使用XSLT 3.0 key函数实现国家名转国家码？

问题背景 #

有一份包含国家名称的SOAP XML数据源，需将其中的sf:ConsumerCountry字段值替换为对应国家码，尝试使用XSLT3.0的key函数实现，但最终JSON输出中sourcecountry字段始终为null。

原SOAP XML数据 #

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns="urn:enter.soap.force.com"
  xmlns:sf="urn:sobject.enter.soap.force.com"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <soapenv:Body>
    <queryMoreResponse>
      <result>
        <records xsi:type="sf:CaseData">
          <sf:Id>6896ADSD888</sf:Id>
          <sf:Number>123456666</sf:Number>
          <sf:ConsumerCountry>Australia</sf:ConsumerCountry>
        </records>
                <records xsi:type="sf:CaseData">
          <sf:Id>6896SDRGGG666</sf:Id>
          <sf:Number>123456666</sf:Number>
          <sf:ConsumerCountry>United States</sf:ConsumerCountry>
        </records>
      </result>
    </queryMoreResponse>
  </soapenv:Body>
</soapenv:Envelope>

原XSLT3.0样式表 #

<xsl:stylesheet version="3.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:sf="urn:sobject.enter.soap.force.com" xpath-default-namespace="urn:enter.soap.force.com"
  xmlns:mf="http://example.com/mf" exclude-result-prefixes="#all">
    
    
    <!-- starts: What I tried -->
  <xsl:key name="countryCodes" match="sf:country" use="sf:name" />
 
  <sf:country name="United States">US</sf:country>
  <sf:country name="Australia">AU</sf:country>
  <sf:country name="Germany">DE</sf:country>
    <!-- ends: What I tried -->
    
    <xsl:function name="mf:process-records" as="item()*">
        <xsl:param name="elements" as="element()*"/>
        <xsl:apply-templates select="$elements"/>
  </xsl:function>

  <xsl:output method="json" indent="yes"/>

  <xsl:template match="/soapenv:Envelope">
    <xsl:map>
      <xsl:map-entry key="'caserecords'" select="array { mf:process-records(soapenv:Body/queryMoreResponse/result/records) }"/>
    </xsl:map>
  </xsl:template>
    <xsl:template match="records">
        <xsl:map-entry key="'case'">
            <xsl:map>
                <xsl:map-entry key="'report'">
                        <xsl:map>
                            <xsl:map-entry key="'reportid'" select="string(sf:Id)"/>
                            <xsl:map-entry key="'reportnumber'" select="string(sf:Number)"/>
                            <!-- starts: What I tried -->
                            <xsl:variable name="countryName" select="string(sf:ConsumerCountry)" />
                            <xsl:variable name="countryCode" select="key('countryCodes', $countryName)" />
                            <xsl:map-entry key="'sourcecountry'" select="$countryCode"/>
                            <!-- ends: What I tried -->
                        </xsl:map>
                </xsl:map-entry>
            </xsl:map>
        </xsl:map-entry>
    </xsl:template>
</xsl:stylesheet>

预期输出 #

{
   "records": [
      {
         "case": {
            "safetyreport": {
               "reportid": "6896ADSD888",
               "reportnumber": "123456666",
               "sourcecountry": "AU"
            }
         }
      },
      {
         "case": {
            "safetyreport": {
               "reportid": "6896SDRGGG666",
               "reportnumber": "123456666",
               "sourcecountry": "US"
            }
         }
      }
   ]
}

错误原因分析 #

1. key函数上下文不匹配：原代码直接将sf:country元素放在样式表顶层，这些元素不属于主输入文档的节点集，而key函数默认仅针对主输入文档节点匹配，因此无法找到映射关系。
2. 取值逻辑错误：即使匹配到sf:country元素，原代码直接将元素本身赋值给字段，而实际需要的是元素的文本内容（国家码）。
3. 结构键名不符：原代码根键为caserecords、内层键为report，与预期输出的records、safetyreport不匹配，导致输出结构不符合要求。

修正后的XSLT3.0样式表 #

方案一：使用XSLT3.0 xsl:map存储映射（推荐，易扩展） #

<xsl:stylesheet version="3.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:sf="urn:sobject.enter.soap.force.com" 
  xpath-default-namespace="urn:enter.soap.force.com"
  exclude-result-prefixes="#all">

  <!-- 定义国家名称到国家码的映射 -->
  <xsl:variable name="countryMap" as="map(xs:string, xs:string)">
    <xsl:map>
      <xsl:map-entry key="'United States'" select="'US'"/>
      <xsl:map-entry key="'Australia'" select="'AU'"/>
      <xsl:map-entry key="'Germany'" select="'DE'"/>
      <!-- 后续可直接添加更多国家映射 -->
    </xsl:map>
  </xsl:variable>

  <xsl:output method="json" indent="yes"/>

  <xsl:template match="/soapenv:Envelope">
    <xsl:map>
      <xsl:map-entry key="'records'" select="array { soapenv:Body/queryMoreResponse/result/records ! mf:process-record(.) }"/>
    </xsl:map>
  </xsl:template>

  <xsl:function name="mf:process-record" as="map(*)">
    <xsl:param name="record" as="element()"/>
    <xsl:map>
      <xsl:map-entry key="'case'">
        <xsl:map>
          <xsl:map-entry key="'safetyreport'">
            <xsl:map>
              <xsl:map-entry key="'reportid'" select="string($record/sf:Id)"/>
              <xsl:map-entry key="'reportnumber'" select="string($record/sf:Number)"/>
              <!-- 从映射中获取国家码，无匹配时可返回原名称或空 -->
              <xsl:map-entry key="'sourcecountry'" select="$countryMap(string($record/sf:ConsumerCountry))"/>
            </xsl:map>
          </xsl:map-entry>
        </xsl:map>
      </xsl:map-entry>
    </xsl:map>
  </xsl:function>

</xsl:stylesheet>

方案二：使用key函数结合变量文档 #

<xsl:stylesheet version="3.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:sf="urn:sobject.enter.soap.force.com" 
  xpath-default-namespace="urn:enter.soap.force.com"
  exclude-result-prefixes="#all">

  <!-- 将国家映射放在变量的文档节点中 -->
  <xsl:variable name="countryDoc">
    <countries>
      <sf:country name="United States">US</sf:country>
      <sf:country name="Australia">AU</sf:country>
      <sf:country name="Germany">DE</sf:country>
    </countries>
  </xsl:variable>

  <!-- 针对变量文档定义key -->
  <xsl:key name="countryCodes" match="sf:country" use="@name" document="$countryDoc"/>

  <xsl:output method="json" indent="yes"/>

  <xsl:template match="/soapenv:Envelope">
    <xsl:map>
      <xsl:map-entry key="'records'" select="array { soapenv:Body/queryMoreResponse/result/records ! mf:process-record(.) }"/>
    </xsl:map>
  </xsl:template>

  <xsl:function name="mf:process-record" as="map(*)">
    <xsl:param name="record" as="element()"/>
    <xsl:variable name="countryName" select="string($record/sf:ConsumerCountry)"/>
    <!-- 指定document参数从变量文档中查找 -->
    <xsl:variable name="countryCode" select="key('countryCodes', $countryName, $countryDoc)/text()"/>
    <xsl:map>
      <xsl:map-entry key="'case'">
        <xsl:map>
          <xsl:map-entry key="'safetyreport'">
            <xsl:map>
              <xsl:map-entry key="'reportid'" select="string($record/sf:Id)"/>
              <xsl:map-entry key="'reportnumber'" select="string($record/sf:Number)"/>
              <xsl:map-entry key="'sourcecountry'" select="$countryCode"/>
            </xsl:map>
          </xsl:map-entry>
        </xsl:map>
      </xsl:map-entry>
    </xsl:map>
  </xsl:function>

</xsl:stylesheet>

修正后输出 #

运行修正后的XSLT，将得到与预期一致的JSON输出：

{
   "records": [
      {
         "case": {
            "safetyreport": {
               "reportid": "6896ADSD888",
               "reportnumber": "123456666",
               "sourcecountry": "AU"
            }
         }
      },
      {
         "case": {
            "safetyreport": {
               "reportid": "6896SDRGGG666",
               "reportnumber": "123456666",
               "sourcecountry": "US"
            }
         }
      }
   ]
}

内容的提问来源于stack exchange，提问作者Rajat Kumar