XSLT：在两个xsl：for-each循环中提取已知前驱的最新DateTime

时间：2015-01-20 19:37:23

标签： xml xslt xpath

给出以下XML：

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <description>
        <program version="2.2.0" type="plain">
            <job id="MyJobID">
                <step id="start_of_job">
                    <param name="begin_time">2014-09-29T16:54:44.920+0200</param>
                    <param name="end_time">2014-09-29T16:54:45.100+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="step_1">
                    <param name="predlist">start_of_job</param>
                    <param name="begin_time">2014-09-29T16:54:49.454+0200</param>
                    <param name="end_time">2014-09-29T16:54:49.473+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="step_2">
                    <param name="predlist">start_of_job</param>
                    <param name="begin_time">2014-09-29T16:54:48.643+0200</param>
                    <param name="end_time">2014-09-29T16:54:48.675+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="step_3">
                    <param name="predlist">step_1</param>
                    <param name="rc">0</param>
                    <param name="begin_time">2014-09-29T16:54:49.442+0200</param>
                    <param name="end_time">2014-09-29T16:54:49.554+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="step_4">
                    <param name="predlist">step_1 step_3</param>
                    <param name="begin_time">2014-09-29T16:54:54.258+0200</param>
                    <param name="end_time">2014-09-29T16:55:49.958+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="step_5">
                    <param name="predlist">step_1 step_2 step_4</param>
                    <param name="begin_time">2014-09-29T16:55:54.550+0200</param>
                    <param name="end_time">2014-09-29T16:55:58.105+0200</param>
                    <param name="state">10</param>
                </step>
                <step id="end_of_job">
                    <param name="predlist">start_of_job step_1 step_2 step_3 step_4 step_5</param>
                    <param name="state">3</param>
                </step>
            </job>
        </program>
    </description>
    <content />
</root>

目标是获取预定列表中已知前任步骤的 end_time ，以计算实际步骤 start_time 与前一步 end_time ，这是给定前辈中的最新一个。例如。对于Step_5，这将是这种情况下Step_4的end_time。但每次都不会这样。步数是可变的。这些步骤是并行处理的，这就是为什么在这种情况下按end_time排序节点不会这样做。但也许我错了。

我对XSLT不太熟悉。这是我到目前为止所知道的：

<xsl:stylesheet
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    xmlns:java="http://xml.apache.org/xslt/java"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:exsl="http://exslt.org/common"
    version="2.0">

    <!-- Add new element -->
    <xsl:output method="xml" indent="yes"/>

    <xsl:template match="/">
        <xsl:for-each select="root/description/program/job/step">
            <xsl:if test="param[@name='state']=10">

                <!-- Retrieve predecessor list -->
                <xsl:variable name="predList" select="tokenize(param[@name='predlist'], ' ')"/>

                <!-- Check which predecessor finished last -->
                <xsl:for-each select="$predList">
                    <xsl:variable name="predecessor" select="."/>
                    <!-- Obtain end_time of predecessor and store it in a xsl:variable e.g. $received__predecessor_end_time somehow -->
                </xsl:for-each>

                <!-- Process ouput XML -->
                <program>
                    <xsl:attribute name="stepID">
                        <xsl:value-of select="@id"/>
                    </xsl:attribute>

                    <xsl:attribute name="waitTime">
                        <!-- Calculate wait time in seconds -->
                        <xsl:call-template name="duration_in_s">
                            <xsl:with-param name="dateTimeBegin" select="substring(param[@name='begin_time'],1,23)"/>
                            <xsl:with-param name="dateTimeEnd" select="substring($received__predecessor_end_time,1,23)"/>
                        </xsl:call-template>
                    </xsl:attribute>
                </program>
            </xsl:if>
        </xsl:for-each>
    </xsl:template>

    <!-- Template: Calculate wait time in seconds -->
    <xsl:template name="duration_in_s">
        <xsl:param name="dateTimeBegin"/>
        <xsl:param name="dateTimeEnd"/>

        <xsl:variable name="DURATION"><xsl:value-of select="xs:dateTime($dateTimeBegin)-xs:dateTime($dateTimeEnd)" /></xsl:variable>
        <xsl:value-of select="((hours-from-duration($DURATION)*3600)+(minutes-from-duration($DURATION)*60)+seconds-from-duration($DURATION))" />
    </xsl:template>
</xsl:stylesheet>

我的问题是xsl：for-each $ predList循环中的范围。在此循环中，我无法访问任何节点以获取其end_time。我想我的做法在这里是错误的。

如何获得$ predList前辈的end_time值＆amp;除了弄清楚哪一个是最新的？

请注意，这可能是多个DateTime值，需要相互比较。可以在这里使用XSLT 2.0。

1 个答案:

答案 0 :(得分：2)

  

如何获得$ predList前辈的end_time值＆amp;除了弄清楚哪一个是最新的？

这应该很简单。只需通过标记当前step并将其与predlist属性进行比较，即可获得相应的id。然后使用max()获取最新的end_time。

参见变量＆＃34; predecessorEndTime＆＃34;在我下面的例子中......

XML输入 

<root>
    <description>
        <program version="2.2.0" type="plain">
            <job id="MyJobID">
                <step id="start_of_job">
                    <param name="begin_time">2014-09-29T16:54:44.920+02:00</param>
                    <param name="end_time">2014-09-29T16:54:45.100+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="step_1">
                    <param name="predlist">start_of_job</param>
                    <param name="begin_time">2014-09-29T16:54:49.454+02:00</param>
                    <param name="end_time">2014-09-29T16:54:49.473+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="step_2">
                    <param name="predlist">start_of_job</param>
                    <param name="begin_time">2014-09-29T16:54:48.643+02:00</param>
                    <param name="end_time">2014-09-29T16:54:48.675+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="step_3">
                    <param name="predlist">step_1</param>
                    <param name="rc">0</param>
                    <param name="begin_time">2014-09-29T16:54:49.442+02:00</param>
                    <param name="end_time">2014-09-29T16:54:49.554+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="step_4">
                    <param name="predlist">step_1 step_3</param>
                    <param name="begin_time">2014-09-29T16:54:54.258+02:00</param>
                    <param name="end_time">2014-09-29T16:55:49.958+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="step_5">
                    <param name="predlist">step_1 step_2 step_4</param>
                    <param name="begin_time">2014-09-29T16:55:54.550+02:00</param>
                    <param name="end_time">2014-09-29T16:55:58.105+02:00</param>
                    <param name="state">10</param>
                </step>
                <step id="end_of_job">
                    <param name="predlist">start_of_job step_1 step_2 step_3 step_4 step_5</param>
                    <param name="state">3</param>
                </step>
            </job>
        </program>
    </description>
    <content />
</root>

XSLT 2.0 （很多xsl:variable试图让您更容易看到正在发生的事情。）

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs">
    <xsl:output indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="/*">
        <results>
            <xsl:apply-templates/>
        </results>
    </xsl:template>

    <xsl:template match="text()"/>

    <xsl:template match="step">
        <xsl:variable name="predecessors" 
            select="tokenize(param[@name='predlist'],'\s')"
            as="item()*"/>
        <xsl:variable name="predecessorEndTime" 
            select="max(../step[@id=$predecessors]/xs:dateTime(param[@name='end_time']))"
            as="xs:dateTime?"/>
        <xsl:variable name="duration" 
            select="xs:dateTime(param[@name='begin_time']) - $predecessorEndTime"
            as="xs:duration?"/>
        <xsl:variable name="waitTime" 
            select="((hours-from-duration($duration)*3600)+
            (minutes-from-duration($duration)*60)+
            seconds-from-duration($duration))"
            as="xs:double?"/>
        <program stepID="{@id}" 
            waitTime="{if ($waitTime) then $waitTime else 0}"/>
    </xsl:template>

</xsl:stylesheet>

XML输出 

<results>
   <program stepID="start_of_job" waitTime="0"/>
   <program stepID="step_1" waitTime="4.354"/>
   <program stepID="step_2" waitTime="3.543"/>
   <program stepID="step_3" waitTime="-0.031"/>
   <program stepID="step_4" waitTime="4.704"/>
   <program stepID="step_5" waitTime="4.592"/>
   <program stepID="end_of_job" waitTime="0"/>
</results>

编辑以回复评论：

如果还有其他不属于job的子项，则可以通过添加此模板将范围缩小到step：

<xsl:template match="job">
    <xsl:apply-templates select="step"/>
</xsl:template>

或者您可以添加此模板以禁止所有其他处理未处理的文本：

<xsl:template match="text()"/>

我用后者更新了我的XSLT示例。

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