根据两个属性值的组合选择唯一节点 [英] Select unique nodes based on a combination of two attribute values

问题描述

我有一些看起来像这样的 XML:

I have some XML that looks something like this:

<Root>
    <Documents>
        <Document id="1"/>
    </Documents>
    <People>
        <Person id="1"/>
        <Person id="2"/>
    </People>
    <Links>
        <Link personId="1" documentId="1"/>
        <Link personId="1" documentId="1"/>
        <Link personId="2" documentId="1"/>
    </Links>
</Root>

而且我只想获取具有personId"和documentId"的独特组合的Link"元素，因此这两个链接:

And I am interested in getting only the 'Link' elements that have a unique combination of 'personId's and 'documentId's, so these two links:

<Root>
    <Links>
        <Link personId="1" documentId="1"/>
        <Link personId="2" documentId="1"/>
    </Links>
</Root>

我该怎么做呢?我发现了这个问题，尽管我觉得我的问题稍微复杂一些并且可能不适用...我想我需要在某处使用 key() 函数...

How might I go about doing that? I have found this question, though I feel mine is slightly more complex and may not apply...I presumme I am going to need to use the key() function somewhere...

提前致谢.

推荐答案

此样式表:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:key name="kDocAndPeoById" match="Document|Person" use="@id"/>
    <xsl:key name="kLinksByIds" match="Link" 
             use="concat(@personId,'++',@documentId)"/>
    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="Documents|People|
     Link[count(.|key('kLinksByIds',concat(@personId,'++',@documentId))[1])!=1
          or not(key('kDocAndPeoById',@personId)/self::Person)
          or not(key('kDocAndPeoById',@documentId)/self::Document)]"/>
</xsl:stylesheet>

输出:

<Root>
    <Links>
        <Link personId="1" documentId="1"></Link>
        <Link personId="2" documentId="1"></Link>
    </Links>
</Root>

如果你没有兴趣检查是否有这样的 Document 或 Person @id，那么这个样式表:

If you have no interest into checking if there is such Document or Person @id, then this stylesheet:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:key name="kLinksByIds" match="Link" 
              use="concat(@personId,'++',@documentId)"/>
    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="Documents|People|
  Link[count(.|key('kLinksByIds',concat(@personId,'++',@documentId))[1])!=1]"/>
</xsl:stylesheet>

输出:

<Root>
    <Links>
        <Link personId="1" documentId="1"></Link>
        <Link personId="2" documentId="1"></Link>
    </Links>
</Root>

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