Problem in Recursive applying template

ismomo · December 20th, 2007, 11:40 PM

Hi all,
I am quite new with xslt, I need advice on how to implement this.
My XML structure:

Code:

        <sub_hierarchy lom_id="341584">
Ã¢Ëâ
    <level id="22">
<title padding="15" type="link" updated_date="2005-05-30 10:43:51" dispatcher_name="Lim Wee Shing Tonny" id="10" have_child="2">lesson 2</title>
Ã¢Ëâ
    <level id="10">
<title padding="30" type="link" updated_date="2005-05-30 10:43:51" dispatcher_name="Lim Wee Shing Tonny" id="90" have_child="1">lesson 3</title>
</level>
</level>
Ã¢Ëâ
    <level id="69">
<title padding="15" type="link" updated_date="2005-05-30 10:43:51" dispatcher_name="Lim Wee Shing Tonny" id="52" have_child="1">testing 2</title>
</level>
</sub_hierarchy>

Here is my XSLT:

Code:

<body>
        <xsl:apply-templates select="level" />
</body>
</xsl:template>
<xsl:template match="level">
    <xsl:for-each select='.'>
    <ul id="ul_menu">
        <xsl:choose>
            <xsl:when test="title">
                <xsl:apply-templates select="title" />
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates name="level" />
            </xsl:otherwise>
        </xsl:choose>
    </ul>
    </xsl:for-each>
</xsl:template>
<xsl:template match="title">
    <xsl:choose>
        <xsl:when test="@have_child &gt; 1">
            <li class="parent">
                <a href="javascript:;" onClick="toggle({@id})" onMouseOver="getInfo(this);" style="padding-left:{@padding}px;
">
                    <img src="/Elearning_Platform/images/plus.gif" />&nbsp;
                    <xsl:value-of select="." />
                </a>
                <input type="hidden" name="lessonplan_Dispatcher" value="{@dispatcher_name}" />
                <input type="hidden" name="lessonplan_Date" value="{@updated_date}" />
            </li>
        </xsl:when>
        <xsl:otherwise>
            <li class="unit">
                <a href="javascript:;" onMouseOver="getInfo(this);" style="padding-left:{@padding}px;">
                    <xsl:value-of select="." />
                </a>
                <input type="hidden" name="lessonplan_Dispatcher" value="{@dispatcher_name}" />
                <input type="hidden" name="lessonplan_Date" value="{@updated_date}" />
            </li>
 </li>
        </xsl:otherwise>
    </xsl:choose>
</xsl:template>
</xsl:stylesheet>

But, it doesn't work as expected. Can anyone tell me to do the right things ? Thanks. The result I would like to have is a tree structure, when found attribute @have_child > 1, it will has a child underneath it.
Lesson 2
Lesson 3
Testing

Thanks.

samjudson · December 21st, 2007, 05:28 AM

Hi

I'm not quite sure what you actual problem is, but here's some pointers about things I've spotted in your XSLT which probably don't work. From there hopefully you can get closer to what you are trying to do.

First, when you call <xsl:apply-templates select="level"/> this will apply the found template once for each level element - it does not pass an 'array' of level elements to that one template.

This means that the <xsl:for-each select="."> statement in your level template is doing nothing - it mealy loops once for the level.

Perhaps what you really wanted to do was select every child of the level element, in which case <xsl:for-each select="*"> is what you are after ("*" is equivalent to "child::*", "." is equivalent to "self::*"). Then your <xsl:if> statement could be changed to <xsl:if test="self::title">.

However as you don't actually do anything with the title or level elements inside the if you might as well get rid of the if completely and just do <xsl:apply-template select="."/>

<xsl:template match="level">
    <xsl:for-each select="child::*">
    <ul id="ul_menu">
         <xsl:apply-templates select="." />
    </ul>
    </xsl:for-each>
</xsl:template>

/- Sam Judson : Wrox Technical Editor -/

mhkay · December 21st, 2007, 06:01 AM

Firstly, <xsl:for-each select="."> is a null operation. You can simply remove it - but try to understand why, because the fact that you wrote it suggests you have some misunderstanding about the way templates work.

In this code

<xsl:choose>
            <xsl:when test="title">
                <xsl:apply-templates select="title" />
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates name="level" />
            </xsl:otherwise>
        </xsl:choose>

I assume the name="level" should be select="level" (it won't even compile as written). With this change, it's saying "if there is a title child, process the title child, otherwise process the level child". Well there's nothing wrong with that, but I suspect that when an element has a title child and a level child then you actually want to process both. Which you can do simply by calling <xsl:apply-templates/> - no xsl:choose needed, no select attribute needed.

When your input contains a level as a direct child of another level, the simple approach will output a ul as a direct child of a ul, which isn't correct HTML - there needs to be an intervening li. One way to achieve this (in XSLT 2.0) is to have a template

<xsl:template match="level/level">
  <li>
    <xsl:next-match/>
  </li>
</xsl:template>

which generates the li element and then implicitly invokes the match="level" template. The next-match instruction isn't available in 1.0; you could achieve it by giving the match="level" template a name and invoking it using call-template.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

ismomo · December 29th, 2007, 11:35 PM

Hi,
Thanks for replying and all the advices been provided. Ya, I realize I did make a mistaken in <xsl:foreach select=".">. Hence, I have make some changes on the code by

Code:

<xsl:template match="sub_hierarchy">
        <ul id="ul_menu"><xsl:apply-templates select="level" /></ul>
</xsl:template>
<xsl:template match="level">
            <xsl:when test="title">
                <xsl:apply-templates select="title" />
            </xsl:when>
            <xsl:otherwise-->
                <xsl:apply-templates />
        </xsl:choose-->
</xsl:template>
<xsl:template match="title">
    <xsl:choose>
        <xsl:when test="@have_child &gt; 1">
        <ul id="ul_menu" style="display:{@display}">
            <li class="parent" id="{../../@lom_id}_{@id}">
                <!--a href="javascript:;" onClick="javascript:alert('why');" onMouseOver="getInfo(this);" style="padding-left
:{@padding}px;"-->
                <a href="javascript:;" onClick="toggle('{../../@lom_id}_{@id}', {@have_child});" style="padding-left:{@paddin
g}px;">

                    <img src="/Elearning_Platform/images/plus.gif" />&nbsp;
                    <xsl:value-of select="." />
                </a>
                <input type="hidden" name="lessonplan_Dispatcher" value="{@dispatcher_name}" />
                <input type="hidden" name="lessonplan_Date" value="{@updated_date}" />
            </li>
        </ul>
        </xsl:when>
     <xsl:otherwise>

            <li class="unit" id="{../@id}" style="display:{@display}">
                <a href="javascript:;" onMouseOver="getInfo(this);" style="padding-left:{@padding}px;">
                    <xsl:value-of select="." />
                </a>
                <input type="hidden" name="lessonplan_Dispatcher" value="{@dispatcher_name}" />
                <input type="hidden" name="lessonplan_Date" value="{@updated_date}" />
                <xsl:choose>
                    <xsl:when test="@type = 0">
                        <input type="hidden" name="lessonplan_Type" value="--" />
                    </xsl:when>
                    <xsl:otherwise>
                        <input type="hidden" name="lessonplan_Type" value="{@type}" />
                    </xsl:otherwise>
                </xsl:choose>
            </li>
        </xsl:otherwise>
    </xsl:choose>
</xsl:template>
</xsl:stylesheet>

The xml structure will be same. But, I have found a problem in grouping all the same parent root into ONE UL. Here, I would like to explain further by taking the example of my previous xml structure,

I would like the structure to be [list]
   <li>Lesson 1</li>
   [list]
      <li>Lesson 1 child 0</li>
      <li>Lesson 1 child 1</li>
   </ul>
   <li>Lesson 2</li>
</ul>

But, my current xslt fail to tie the relationship of parent and child together when it is more than 2 level. Thanks for advice.