Question

I have an XML document that models this hierarchy of tasks:

1     Customer
1.1   Product A
1.1.1 Task Alpha
1.1.2 Task Beta
1.2   Product B
1.2.1 Task Alpha
1.2.2 Task Gamma
2     Customer
2.1   Product W
2.1.1 Task Delta

Unknown number of Customers, Products, and Tasks per product. There can also be an unknown number of subtasks, so we could see this:

19.16.8.17.1 Subtask Something

The XML looks like this:

<ROWSET>
    <ROW>
        <PROJECT_CODE>Don't Care</PROJECT_CODE>
    </ROW>
    <ROW>
        <PROJECT_CODE>WBS</PROJECT_CODE>
        <TASK_DETAIL>
            <TASKS>
                <TASK>
                    <TASK_CODE>1</TASK_CODE>
                    <TASK_DESCRIPTION>Customer 1</TASK_DESCRIPTION>
                    <TASKS>
                        <TASK>
                            <TASK_CODE>1.1</TASK_CODE>
                            <TASK_DESCRIPTION>Product A</TASK_DESCRIPTION>
                            <TASKS>
                                <TASK_CODE>1.1.1</TASK_CODE>
                                <TASK_DESCRIPTION>Task Alpha</TASK_DESCRIPTION>
                                <TASKS />
                                <TASK_CODE>1.1.2</TASK_CODE>
                                <TASK_DESCRIPTION>Task Beta</TASK_DESCRIPTION>
                                <TASKS />
                            </TASKS>
                        </TASK>
                        <TASK>
                            <TASK_CODE>1.2</TASK_CODE>
                            <TASK_DESCRIPTION>Product B</TASK_DESCRIPTION>
                            <TASKS>
                                <TASK_CODE>1.2.1</TASK_CODE>
                                <TASK_DESCRIPTION>Task Alpha</TASK_DESCRIPTION>
                                <TASKS />
                                <TASK_CODE>1.2.2</TASK_CODE>
                                <TASK_DESCRIPTION>Task Gamma</TASK_DESCRIPTION>
                                <TASKS />
                            </TASKS>
                        </TASK>
                    </TASKS>
                </TASK>
                <TASK>
                    <TASK_CODE>2</TASK_CODE>
                    <TASK_DESCRIPTION>Customer 2</TASK_DESCRIPTION>
                    <TASKS>
                        <TASK>
                            <TASK_CODE>2.1</TASK_CODE>
                            <TASK_DESCRIPTION>Product W</TASK_DESCRIPTION>
                            <TASKS>
                                <TASK_CODE>2.1.1</TASK_CODE>
                                <TASK_DESCRIPTION>Task Delta</TASK_DESCRIPTION>
                                <TASKS />
                            </TASKS>
                        </TASK>
                    </TASKS>
                </TASK>
            </TASKS>
        </TASK_DETAIL>
    </ROW>
</ROWSET>

My first attempt at an XSLT is this:

<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="ROW">
    <xsl:apply-templates select="PROJECT_CODE[.='WBS']"/>
</xsl:template>
<xsl:template match="PROJECT_CODE">
    <h1><xsl:value-of select="."/></h1>
    <table>
        <tr>
            <th>Task Code</th>
            <th>Description</th>
        </tr>
        <xsl:for-each select="./../TASK_DETAIL/TASKS/TASK">
        <tr>
            <td><xsl:value-of select="TASK_CODE"/></td>
            <td><xsl:value-of select="TASK_DESCRIPTION"/></td>
        </tr>
            <xsl:for-each select="./TASKS/TASK">
                <tr>
                    <td><xsl:value-of select="TASK_CODE"/></td>
                    <td><xsl:value-of select="TASK_DESCRIPTION"/></td>
                </tr>
            </xsl:for-each>
        </xsl:for-each>
    </table>
</xsl:template>

As you can see, I’m taking a very naive approach to parsing this thing. I would like to list all the tasks & subtasks of my particular WBS, no matter how many levels deep it goes. How do I do that?

Answer 1

Looks like musikk beat me to an explanation, but here’s a demo xslt that does what I understand you want. In general, avoid xsl:for-each for most of the things you think you should use for-each for (i.e. for which you would use for-each in other languages). Instead, use apply-templates or call-templates as musikk says. Read up on modes (mode=”foo”) too if you have to process the same content several times (e.g. to generate a table of contents and then the body and then an index).

    <?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <html>
      <body>
        <xsl:apply-templates/>
      </body>
    </html>
  </xsl:template>
  <xsl:template match="ROW[./PROJECT_CODE='WBS']">
    <h1><xsl:value-of select="PROJECT_CODE"/></h1>
    <table>
      <tr>
        <th>Task Code</th>
        <th>Description</th>
      </tr>
      <xsl:apply-templates/>
    </table>
  </xsl:template>
  <xsl:template match="TASK">
    <tr>
      <td><xsl:value-of select="TASK_CODE"/></td>
      <td><xsl:value-of select="TASK_DESCRIPTION"/></td>
    </tr>
    <xsl:apply-templates/>
  </xsl:template>
  <xsl:template match="text()"/>
</xsl:stylesheet>

This produces:

    <html>
   <body>
      <h1>WBS</h1>
      <table>
         <tr>
            <th>Task Code</th>
            <th>Description</th>
         </tr>
         <tr>
            <td>1</td>
            <td>Customer 1</td>
         </tr>
         <tr>
            <td>1.1</td>
            <td>Product A</td>
         </tr>
         <tr>
            <td>1.2</td>
            <td>Product B</td>
         </tr>
         <tr>
            <td>2</td>
            <td>Customer 2</td>
         </tr>
         <tr>
            <td>2.1</td>
            <td>Product W</td>
         </tr>
      </table>
   </body>
</html>