xml - XSLT:基于 2 个子元素的元素的数学加法

Question

我正在尝试根据帐号和与金额关联的货币添加交易。

这是原始的 xml:我希望最多有 1000 笔交易。在示例中，我有来自 2 个澳元和港元账户的 5 笔交易。我希望将每种货币、每笔交易的所有金额添加为 1 行。

<transactionlist>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>100</amount>
        <currency>AUD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>50</amount>
        <currency>AUD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>100</amount>
        <currency>HKD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>500</amount>
        <currency>HKD</currency>
    </transaction>
    <transaction>
        <accountnumber>2</accountnumber>
        <amount>200</amount>
        <currency>AUD</currency>
    </transaction>
</transactionlist>

这是预期的输出(计算添加了多少事务来创建新行):

<transactionlist>
    <row>
        <accountnumber>1</accountnumber>
        <totalamount>150</totalamount>
        <currency>AUD</currency>
        <count>2</count>
    </row>
    <row>
        <accountnumber>1</accountnumber>
        <totalamount>600</totalamount>
        <currency>HKD</currency>
        <count>2</count>
    </row>
    <row>
        <accountnumber>2</accountnumber>
        <totalamount>200</totalamount>
        <currency>AUD</currency>
        <count>1</count>
    </row>
</transactionlist>

这是我得到的结果。只是不确定如何为按帐户分组的每笔交易仅按货币添加

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:template match="/">
    <transactionlist>
      <xsl:apply-templates select="transactionlist/transaction" />
    </transactionlist>
  </xsl:template>

  <xsl:template match="transaction">
    <!-- only do work for the *first* transaction with any particular ID -->
    <xsl:if test="not(preceding-sibling::transaction/accountnumber = current()/accountnumber)">
      <row>
        <xsl:copy-of select="accountnumber" />
        <totalamount>
          <xsl:call-template name="running-total-byaccount">
            <xsl:with-param name="values" select="/transactionlist/transaction[accountnumber = current()/accountnumber]" />
          </xsl:call-template>
        </totalamount>
      </row>
    </xsl:if>
  </xsl:template>

  <xsl:template name="running-total-byaccount">
    <xsl:param name="values" />
    <xsl:choose>
      <xsl:when test="count($values)">
        <xsl:variable name="curr" select="$values[1]" />
        <xsl:variable name="rest" select="$values[position() &gt; 1]" />
        <!-- recursive step: calculate the total of all remaining values -->
        <xsl:variable name="subtotal">
          <xsl:call-template name="running-total-byaccount">
            <xsl:with-param name="values" select="$rest" />
          </xsl:call-template>
        </xsl:variable>
        <xsl:value-of select="$subtotal + $curr/amount" />
      </xsl:when>
      <xsl:otherwise>
        <xsl:value-of select="0" />
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>


</xsl:stylesheet>

Answer 1

您在使用 XSLT 时采用命令式“类似编程”的方法太深入了。我向我的学生推荐使用分组方法的自上而下的声明式方法是处理像您这样的需求的最佳方法。

在 XSLT 1.0 的分组方法中，由于组的嵌套性质，您的问题向我建议了基于变量的分组方法。 XSLT 2.0 使这更容易，但您已经在样式表中声明了 XSLT 1.0，所以我认为这对您来说是一个限制。

我拼凑的一个快速解决方案在下面的文字记录中。我希望这有帮助。您可以看到它避免了所有递归问题并将需求分解为分组问题。

数据:

T:\ftemp>type currency.xml 
<transactionlist>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>100</amount>
        <currency>AUD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>50</amount>
        <currency>AUD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>100</amount>
        <currency>HKD</currency>
    </transaction>
    <transaction>
        <accountnumber>1</accountnumber>
        <amount>500</amount>
        <currency>HKD</currency>
    </transaction>
    <transaction>
        <accountnumber>2</accountnumber>
        <amount>200</amount>
        <currency>AUD</currency>
    </transaction>
</transactionlist>

执行和结果:

T:\ftemp>call xslt currency.xml currency.xsl 
<?xml version="1.0" encoding="utf-8"?>
<transactionlist>
   <row>
      <accountnumber>1</accountnumber>
      <totalamount>150</totalamount>
      <currency>AUD</currency>
      <count>2</count>
   </row>
   <row>
      <accountnumber>1</accountnumber>
      <totalamount>600</totalamount>
      <currency>HKD</currency>
      <count>2</count>
   </row>
   <row>
      <accountnumber>2</accountnumber>
      <totalamount>200</totalamount>
      <currency>AUD</currency>
      <count>1</count>
   </row>
</transactionlist>

样式表:

T:\ftemp>type currency.xsl 
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">

<xsl:output indent="yes"/>

<xsl:template match="transactionlist">
  <transactionlist>
    <xsl:variable name="trans" select="transaction"/>
    <xsl:for-each select="$trans">
      <!--find all unique accounts-->
      <xsl:if test="generate-id(.)=
             generate-id($trans[accountnumber=current()/accountnumber][1])">
        <xsl:variable name="acc" 
                    select="$trans[accountnumber=current()/accountnumber]"/>
        <xsl:for-each select="$acc">
          <!--find all unique currencies in the accounts-->
          <xsl:if test="generate-id(.)=
                        generate-id($acc[currency=current()/currency][1])">
            <!--note all for the given currency-->
            <xsl:variable name="curr"
                          select="$acc[currency=current()/currency]"/>
            <row>
              <xsl:copy-of select="accountnumber"/>
              <totalamount>
                <xsl:value-of select="sum($curr/amount)"/>
              </totalamount>
              <xsl:copy-of select="currency"/>
              <count>
                <xsl:value-of select="count($curr)"/>
              </count>
            </row>            
          </xsl:if>
        </xsl:for-each>
      </xsl:if>
    </xsl:for-each>
  </transactionlist>
</xsl:template>

</xsl:stylesheet>

已编辑:修复拼写错误并收集货币值以提高可读性。