Question

I have to make xPath dynamical, based on my request attributes in XSL file making JSP using expression language. So now I have this thing:

<xsl:variable name="xPath">@name='${categoryName}'</xsl:variable>
<xsl:for-each select="tar:products/category[$xPath]/subcategory">

But this doesn’t work. So the question is how to get round this problem and make xPath work?

---

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE tar:products SYSTEM "products.dtd" >
<?xml-stylesheet type='text/xsl' href='products2HTML.xsl'?>
<tar:products xmlns:tar="http://www.epam.com/products"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.epam.com/products products.xsd ">
<category name="Electronics">
    <subcategory name="mp3">
        <product name="iPod 4g">
            <provider>Apple</provider>
            <model>Qd246</model>
            <dateOfIssue>11-11-2012</dateOfIssue>
            <color>white</color>
            <notInStock/>
        </product>
        <product name="Cowon">
            <provider>Cowon</provider>
            <model>sF223</model>
            <dateOfIssue>13-12-2012</dateOfIssue>
            <color>black</color>
            <price>13456</price>
        </product>
        <product name="IRiver">
            <provider>IRiver e30</provider>
            <model>Ir234</model>
            <dateOfIssue>13-12-2012</dateOfIssue>
            <color>black</color>
            <price>13456</price>
        </product>
    </subcategory>
    <subcategory name="Computers">
        <product name="iMac">
            <provider>Apple</provider>
            <model>Mm232</model>
            <dateOfIssue>20-02-2012</dateOfIssue>
            <color>silver</color>
            <notInStock/>
        </product>
        <product name="PC">
            <provider>Acer</provider>
            <model>Ae135</model>
            <dateOfIssue>22-11-2012</dateOfIssue>
            <color>black</color>
            <price>13456</price>
        </product>
    </subcategory>
</category>
<category name="Toys">
    <subcategory name="Electronical toys">
        <product name="Cat">
            <provider>UrkToy</provider>
            <model>cC246</model>
            <dateOfIssue>11-11-2012</dateOfIssue>
            <color>grey</color>
            <price>1100</price>
        </product>
        <product name="Dog">
            <provider>LatToy</provider>
            <model>Ld223</model>
            <dateOfIssue>03-12-2012</dateOfIssue>
            <color>white</color>
            <price>13456</price>
        </product>
    </subcategory>
    <subcategory name="Fabric toys">
        <product name="Bear">
            <provider>RusToy</provider>
            <model>BB122</model>
            <dateOfIssue>20-02-2012</dateOfIssue>
            <color>brown</color>
            <notInStock/>
        </product>
        <product name="Bird">
            <provider>BelToy</provider>
            <model>Bb110</model>
            <dateOfIssue>05-11-2012</dateOfIssue>
            <color>red</color>
            <price>500</price>
        </product>
    </subcategory>
</category>
</tar:products>

---

I put parameter categoryName in request from my previous page and it’s successfully shown on my page, so problem is not in it.
Here is more info about xsl file:

<?xml version="1.0" encoding="UTF-8"?>

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
xmlns:tar="http://www.epam.com/products"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.epam.com/products products.xsd ">
<xsl:output method="html" />
<xsl:param name="categoryName" select="'${categoryName}'"></xsl:param>
<xsl:template match="/">
    <table border="1">
        <tr bgcolor="#CCCCCC">
            <td align="center">
                <strong>
                    Subcategories
                            </strong>
            </td>
        </tr>
        <xsl:value-of select="$categoryName"/><!-- this string works -->
        <xsl:for-each select="tar:products/category[@name=$categoryName]/subcategory">
            <xsl:sort order="descending" select="count(product)"
                data-type="number" />
            <a href="controller?command=products&amp;name={@name}">
            <tr bgcolor="#F5F5F5">
                <td>
                    <xsl:value-of select="@name" />
                    (
                    <xsl:value-of select="count(product)" />
                    )
                </td>

            </tr>
            </a>
        </xsl:for-each>
    </table>
    <form method="post" action="/controller?command=back">
        <input type="submit" value="Back"/>
    </form>
</xsl:template>
 </xsl:stylesheet>

---

Expected output,when request parameter categoryName equals 'Toys':

---

Actual output:

---

RESOVLED

In my java class I’ve put parameter in request before transformation, but needed simply to put it in transformator parameters:

transformer.setParameter("categoryName", name);

Answer 1

If you really need to have dynamically built XPath, you will need to make use of an extension function. For example, you may be able to use the EXSTL Dynamic Extension Function.

However, looking at your rather terse code sample, I am not sure you need the extra complexity in this case. Could you two lines be simplified to the following:

<xsl:for-each select="tar:products/category[@name=$categoryName]/subcategory">