XSLT concat string, remove last comma

问题:

I need to build up a string using XSLT and separate each string with a comma but not include a comma after the last string. In my example below I will have a trailing comma if I have Distribution node and not a Note node for instance. I don't know of anyway to build up a string as a variable and then truncate the last character in XSLT. Also this is using the Microsoft XSLT engine.

My String =

<xsl:if test="Locality != ''">
  <xsl:value-of select="Locality"/>,
</xsl:if>
<xsl:if test="CollectorAndNumber != ''">
  <xsl:value-of select="CollectorAndNumber"/>,
</xsl:if>
<xsl:if test="Institution != ''">
  <xsl:value-of select="Institution"/>,
</xsl:if>
<xsl:if test="Distribution != ''">
  <xsl:value-of select="Distribution"/>,
</xsl:if>
<xsl:if test="Note != ''">
  <xsl:value-of select="Note"/>
</xsl:if>

[Man there's gotta be a better way to enter into this question text box :( ]

回答1:

This is very easy to accomplish with XSLT (No need to capture the results in a variable, or to use special named templates):

I. XSLT 1.0:

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

    <xsl:template match="/*/*">
      <xsl:for-each select=
      "Locality/text() | CollectorAndNumber/text()
     | Institution/text() | Distribution/text()
     | Note/text()
      "
      >
        <xsl:value-of select="."/>
        <xsl:if test="not(position() = last())">,</xsl:if>
      </xsl:for-each>
    </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the following XML document:

<root>
    <record>
        <Locality>Locality</Locality>
        <CollectorAndNumber>CollectorAndNumber</CollectorAndNumber>
        <Institution>Institution</Institution>
        <Distribution>Distribution</Distribution>
        <Note></Note>
        <OtherStuff>Unimportant</OtherStuff>
    </record>
</root>

the wanted result is produced:

Locality,CollectorAndNumber,Institution,Distribution

If the wanted elements should be produced not in document order (something not required in the question, but raised by Tomalak), it is still quite easy and elegant to achieve this:

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

    <xsl:param name="porderedNames"
     select="' CollectorAndNumber Locality Distribution Institution Note '"/>

    <xsl:template match="/*/*">
        <xsl:for-each select=
         "*[contains($porderedNames, concat(' ',name(), ' '))]">

         <xsl:sort data-type="number"
          select="string-length(
                     substring-before($porderedNames,
                                      concat(' ',name(), ' ')
                                      )
                                )"/>

            <xsl:value-of select="."/>
            <xsl:if test="not(position() = last())">,</xsl:if>
        </xsl:for-each>
    </xsl:template>
</xsl:stylesheet>

Here the names of the wanted elements and their wanted order are provided in the string parameter $porderedNames, which contains a space-separated list of all wanted names.

When the above transformation is applied on the same XML document, the wanted result is produced:

CollectorAndNumber,Locality,Distribution,Institution

---

II. XSLT 2.0:

In XSLT this task is even simpler (again, no special function is necessary):

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output method="text"/>

    <xsl:template match="/*/*">
    <xsl:value-of separator="," select=
    "(Locality, CollectorAndNumber,
     Institution, Distribution,
     Note)[text()]" />
    </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the same XML document, the same correct result is produced:

Locality,CollectorAndNumber,Institution,Distribution

Do note that the wanted elements will be produced in any desired order, because we are using the XPath 2.0 sequence type (vs the union in the XSLT 1.0 solution), which by definition contains items in any desired (specified) order.

回答2:

I would prefer a short call-template to join the node values together. This also works if a node in the middle of your concatenated list, e.g. Institution, is missing:

<xsl:template name="join">
    <xsl:param name="list" />
    <xsl:param name="separator"/>

    <xsl:for-each select="$list">
        <xsl:value-of select="." />
        <xsl:if test="position() != last()">
            <xsl:value-of select="$separator" />
        </xsl:if>
    </xsl:for-each>
</xsl:template>

Here is a short example how to use it:

Sample input document:

<?xml version="1.0" encoding="utf-8"?>
<items>
  <item>
    <Locality>locality1</Locality>
    <CollectorAndNumber>collectorAndNumber1</CollectorAndNumber>
    <Distribution>distribution1</Distribution>
    <Note>note1</Note>
  </item>
  <item>
    <Locality>locality2</Locality>
    <CollectorAndNumber>collectorAndNumber2</CollectorAndNumber>
    <Institution>institution2</Institution>
    <Distribution>distribution2</Distribution>
    <Note>note2</Note>
  </item>
  <item>
    <Locality>locality3</Locality>
    <CollectorAndNumber>collectorAndNumber3</CollectorAndNumber>
    <Institution>institution3</Institution>
    <Distribution>distribution3</Distribution>
  </item>
</items>

XSL transformation:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes"/>

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

  <xsl:template match="item">
    <item>
      <xsl:call-template name="join">
        <xsl:with-param name="list" select="Locality | CollectorAndNumber | Institution | Distribution | Note" />
        <xsl:with-param name="separator" select="','" />
      </xsl:call-template>
    </item>
  </xsl:template>

  <xsl:template name="join">
    <xsl:param name="list" />
    <xsl:param name="separator"/>

    <xsl:for-each select="$list">
      <xsl:value-of select="." />
      <xsl:if test="position() != last()">
        <xsl:value-of select="$separator" />
      </xsl:if>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>

Generated output document:

<?xml version="1.0" encoding="utf-8"?>
<summary>
  <item>locality1,collectorAndNumber1,distribution1,note1</item>
  <item>locality2,collectorAndNumber2,institution2,distribution2,note2</item>
  <item>locality3,collectorAndNumber3,institution3,distribution3</item>
</summary>

NB: If you were using XSLT/XPath 2.0 then there would be fn:string-join

fn:string-join**($operand1 as string*, $operand2 as string*) as string

which could be used as follows:

fn:string-join({Locality, CollectorAndNumber, Distribution, Note}, ",") 

回答3:

Supposing you have something like the following input XML:

<root>
  <record>
    <Locality>Locality</Locality>
    <CollectorAndNumber>CollectorAndNumber</CollectorAndNumber>
    <Institution>Institution</Institution>
    <Distribution>Distribution</Distribution>
    <Note>Note</Note>
    <OtherStuff>Unimportant</OtherStuff>
  </record>
</root>

Then this template would do it:

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

  <xsl:output method="text" />

  <xsl:template match="record">
    <xsl:variable name="values">
      <xsl:apply-templates mode="concat" select="Locality" />
      <xsl:apply-templates mode="concat" select="CollectorAndNumber" />
      <xsl:apply-templates mode="concat" select="Institution" />
      <xsl:apply-templates mode="concat" select="Distribution" />
      <xsl:apply-templates mode="concat" select="Note" />
    </xsl:variable>

    <xsl:value-of select="substring($values, 1, string-length($values) - 1)" />
    <xsl:value-of select="'&#10;'" /><!-- LF -->
  </xsl:template>

  <xsl:template match="Locality | CollectorAndNumber | Institution | Distribution | Note" mode="concat">
    <xsl:value-of select="." />
    <xsl:text>,</xsl:text>
  </xsl:template>

</xsl:stylesheet>

Output on my system:

Locality,CollectorAndNumber,Institution,Distribution,Note

回答4:

I think it might be useful to mention, position() doesn't work right when I use a complicated select that filters some nodes, in that case I came up which this trick:

you can define a string variable that hold value of nodes, separated by a specific character, then by using str:tokenize() you can create a complete node list which position works fine with it.

something like this:

<!-- Since position() doesn't work as expected(returning node position of current 
node list), I got round it by a string variable and tokenizing it in which 
absolute position is equal to relative(context) position. -->
<xsl:variable name="measObjLdns" >
    <xsl:for-each select="h:measValue[@measObjLdn=$currentMeasObjLdn]/h:measResults" >
        <xsl:value-of select="concat(.,'---')"/> <!-- is an optional separator. -->
    </xsl:for-each>
</xsl:variable>

<xsl:for-each select="str:tokenize($measObjLdns,'---')" ><!-- Since position() doesn't 

work as expected(returning node position of current node list), 
I got round it by a string variable and tokenizing it in which
absolute position is equal to relative(context) position. -->

    <xsl:value-of select="."></xsl:value-of>
    <xsl:if test="position() != last()">
        <xsl:text>,</xsl:text>
    </xsl:if>
</xsl:for-each>
<xsl:if test="position() != last()">
    <xsl:text>,</xsl:text>
</xsl:if>

回答5:

Do you not have a value that is always going to be there? If you do then you can turn it around and put commas infront of everything apart from the first item (which would be your value that's always there).

回答6:

This would be a bit messy but might do the trick if there's only a few elements like in your example:

<xsl:if test="Locality != ''">
    <xsl:value-of select="Locality"/>
    <xsl:if test="CollectorAndNumber != '' or Institution != '' or Distribution != '' or Note != ''">
        <xsl:value-of select="','"/>
    </xsl:if>
</xsl:if>
<xsl:if test="CollectorAndNumber != ''">
    <xsl:value-of select="CollectorAndNumber"/>
    <xsl:if test="Institution != '' or Distribution != '' or Note != ''">
        <xsl:value-of select="','"/>
    </xsl:if>
</xsl:if>
<xsl:if test="Institution != ''">
    <xsl:value-of select="Institution"/>
    <xsl:if test="Distribution != '' or Note != ''">
        <xsl:value-of select="','"/>
    </xsl:if>
</xsl:if>
<xsl:if test="Distribution != ''">
    <xsl:value-of select="Distribution"/>
    <xsl:if test="Note != ''">
        <xsl:value-of select="','"/>
    </xsl:if>
</xsl:if>
<xsl:if test="Note != ''">
    <xsl:value-of select="Note"/>
</xsl:if>