XSL if else condition

问题:

I have a requirement where I'd like to have if else statement to check whether a node has attributes or it has just string.

Eg: 1 of the node has 0 File(s) found and the other has attribs such as <autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='64' filename='AFP_p.tgp' />

Below is a sample of two nodes

<product>
<autoIncludeUser>0 File(s) found</autoIncludeUser>
<autoIncludeSystem>
<autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='64' filename='AFP_p.tgp' />
<autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='3,879' filename='AnalystsExpressionMacros.tgp' />
<autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='475' filename='base64Converter.tgp' />
<autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='&lt;DIR&gt;' filename='codePages' />
</autoIncludeSystem>
<autoIncludeStudio>0 File(s) found</autoIncludeStudio>
<externalLibrarySystem>
<externalLibrarySystem_info mdate='08/23/2011' mtime='09:52' ampm='PM' filesize='196,608' filename='AFPtoXML_DP.dll' />
<externalLibrarySystem_info mdate='08/23/2011' mtime='09:52' ampm='PM' filesize='13,259' filename='ASN1toXSDRunner.jar' />
<externalLibrarySystem>
</product>

How would i identify if a node has just strings or attribs and based on that I can get the values either String or attrib values respectively.

回答1:

You can replace your whole xsl:choose instruction with:

<xsl:apply-templates select="autoIncludeSystem"/>

and then add two templates:

<xsl:template match="autoIncludeSystem[autoincludesystem_info/@*]>
  <!-- code for elements with attributes (xsl:when) -->
</xsl:template>


<xsl:template match="autoIncludeSystem[not(autoincludesystem_info/@*)]>
  <!-- code for elements without attributes (xsl:otherwise) -->
</xsl:template>

回答2:

We can achieve if else by using below code

<xsl:choose>
    <xsl:when test="something to test">

    </xsl:when>
    <xsl:otherwise>

    </xsl:otherwise>
</xsl:choose>

So here is what I did

<h3>System</h3>
    <xsl:choose>
        <xsl:when test="autoIncludeSystem/autoincludesystem_info/@mdate"> <!-- if attribute exists-->
            <p>
                <dd><table border="1">
                    <tbody>
                        <tr>
                            <th>File Name</th>
                            <th>File Size</th>
                            <th>Date</th>
                            <th>Time</th>
                            <th>AM/PM</th>
                        </tr>
                        <xsl:for-each select="autoIncludeSystem/autoincludesystem_info">
                            <tr>
                                <td valign="top" ><xsl:value-of select="@filename"/></td>
                                <td valign="top" ><xsl:value-of select="@filesize"/></td>
                                <td valign="top" ><xsl:value-of select="@mdate"/></td>
                                <td valign="top" ><xsl:value-of select="@mtime"/></td>
                                <td valign="top" ><xsl:value-of select="@ampm"/></td>
                            </tr>
                        </xsl:for-each>
                    </tbody>
                </table>
                </dd>
            </p>
        </xsl:when>
        <xsl:otherwise> <!-- if attribute does not exists -->
            <dd><pre>
                <xsl:value-of select="autoIncludeSystem"/><br/>
            </pre></dd> <br/>
        </xsl:otherwise>
    </xsl:choose>

My Output

回答3:

I. Xpath 1.0 solution - use this single XPath expression:

concat(substring('String', 1 div boolean(text())),
                 ' ',
       substring('attrib values', 1 div boolean(@*))
       )

Here is a XSLT-based verification:

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

 <xsl:template match="*[not(*)]">
     <xsl:value-of select="concat('&#10;', name(),': ')"/>

     <xsl:value-of select=
      "concat(substring('String', 1 div boolean(text())),
              ' ',
              substring('attrib values', 1 div boolean(@*))
             )
      "/>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the provided XML document (slightly corrected to be made well-formed):

<product>
    <autoIncludeUser>0 File(s) found</autoIncludeUser>
    <autoIncludeSystem>
        <autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='64' filename='AFP_p.tgp' />
        <autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='3,879' filename='AnalystsExpressionMacros.tgp' />
        <autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='475' filename='base64Converter.tgp' />
        <autoincludesystem_info mdate='08/23/2011' mtime='09:51' ampm='PM' filesize='&lt;DIR&gt;' filename='codePages' />
    </autoIncludeSystem>
    <autoIncludeStudio>0 File(s) found</autoIncludeStudio>
    <externalLibrarySystem>
        <externalLibrarySystem_info mdate='08/23/2011' mtime='09:52' ampm='PM' filesize='196,608' filename='AFPtoXML_DP.dll' />
        <externalLibrarySystem_info mdate='08/23/2011' mtime='09:52' ampm='PM' filesize='13,259' filename='ASN1toXSDRunner.jar' />
    </externalLibrarySystem>
</product>

the wanted, correct result is produced:

autoIncludeUser: String 
autoincludesystem_info:  attrib values
autoincludesystem_info:  attrib values
autoincludesystem_info:  attrib values
autoincludesystem_info:  attrib values
autoIncludeStudio: String 
externalLibrarySystem_info:  attrib values
externalLibrarySystem_info:  attrib values

Explanation We use these facts:

1. For any string $s, substring($s, Infinity) is the empty string.

2. 1 div 0 is Infinity

3. By definition number(true()) is 1 and number(false()) is 0.

   II. XPath 2.0 solution:

This is much easier in XPath 2.0 because the language has standard if/then/else operator.

Use:

if(text())
  then 'String'
  else if(@*)
         then 'attrib values'
         else ()

XSLT 2.0 verification:

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

 <xsl:template match="*[not(*)]">
     <xsl:value-of select="concat('&#10;', name(),': ')"/>

     <xsl:value-of select=
      "if(text())
         then 'String'
         else if(@*)
           then 'attrib values'
           else ()
      "/>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the same XML document (above), again the wanted, correct result is produced:

autoIncludeUser: String
autoincludesystem_info: attrib values
autoincludesystem_info: attrib values
autoincludesystem_info: attrib values
autoincludesystem_info: attrib values
autoIncludeStudio: String
externalLibrarySystem_info: attrib values
externalLibrarySystem_info: attrib values

回答4:

XPath //*[not(@*)] will select all elements, which don't have attributes.

回答5:

You can do this easily enough using xsl:choose - but very often in XSLT, the better way to do conditional processing is to write different template rules to handle the different conditions. So write one template rule with match="*[@*]" to match elements that have attributes, and another with match="*[text()]" to match elements that have textual content.