XSLT <sort>
Sorting XML data in your output
🔢 What is <xsl:sort>?
The <xsl:sort> element sorts nodes before processing them. It's used inside <xsl:for-each> or <xsl:apply-templates> to arrange data alphabetically, numerically, or in custom order.
<!-- Sort by title -->
<xsl:for-each select="book">
<xsl:sort select="title"/>
</xsl:for-each>
Understanding <sort>
The <xsl:sort> element organizes XML nodes in a specific order before they are processed. You can sort alphabetically, numerically, in ascending or descending order, making your output data well-organized and easy to read.
Alphabetical Sort
Sort text data A-Z
<xsl:sort select="name"/>Numerical Sort
Sort numbers correctly
<xsl:sort select="price"
data-type="number"/>Ascending Order
Low to high (default)
order="ascending"Descending Order
High to low
order="descending"🔹 Basic Alphabetical Sort
Sort books alphabetically by title:
XML Data:
<?xml version="1.0"?>
<library>
<book><title>Zebra Tales</title></book>
<book><title>Apple Recipes</title></book>
<book><title>Mountain Climbing</title></book>
</library>XSLT Template:
<xsl:template match="library">
<h3>Books (Sorted A-Z):</h3>
<ul>
<xsl:for-each select="book">
<xsl:sort select="title"/>
<li><xsl:value-of select="title"/></li>
</xsl:for-each>
</ul>
</xsl:template>Output:
Books (Sorted A-Z):
- Apple Recipes
- Mountain Climbing
- Zebra Tales
🔹 Numerical Sort
Sort products by price using numerical sorting:
XML Data:
<products>
<product>
<name>Laptop</name>
<price>999</price>
</product>
<product>
<name>Mouse</name>
<price>25</price>
</product>
<product>
<name>Keyboard</name>
<price>75</price>
</product>
</products>XSLT Template:
<xsl:template match="products">
<h3>Products by Price:</h3>
<ul>
<xsl:for-each select="product">
<xsl:sort select="price" data-type="number"/>
<li>
<xsl:value-of select="name"/> -
$<xsl:value-of select="price"/>
</li>
</xsl:for-each>
</ul>
</xsl:template>Output:
Products by Price:
- Mouse - $25
- Keyboard - $75
- Laptop - $999
🔹 Descending Order Sort
Sort in reverse order from high to low:
XML Data:
<students>
<student>
<name>Alice</name>
<score>85</score>
</student>
<student>
<name>Bob</name>
<score>92</score>
</student>
<student>
<name>Charlie</name>
<score>78</score>
</student>
</students>XSLT Template:
<xsl:template match="students">
<h3>Top Scores:</h3>
<ol>
<xsl:for-each select="student">
<xsl:sort select="score" data-type="number"
order="descending"/>
<li>
<xsl:value-of select="name"/> -
<xsl:value-of select="score"/> points
</li>
</xsl:for-each>
</ol>
</xsl:template>Output:
Top Scores:
- Bob - 92 points
- Alice - 85 points
- Charlie - 78 points
🔹 Multiple Sort Criteria
Sort by multiple fields - first by category, then by name:
XML Data:
<items>
<item category="B">Zebra</item>
<item category="A">Lion</item>
<item category="B">Apple</item>
<item category="A">Tiger</item>
</items>XSLT Template:
<xsl:template match="items">
<ul>
<xsl:for-each select="item">
<xsl:sort select="@category"/>
<xsl:sort select="."/>
<li>
[<xsl:value-of select="@category"/>]
<xsl:value-of select="."/>
</li>
</xsl:for-each>
</ul>
</xsl:template>Output:
- [A] Lion
- [A] Tiger
- [B] Apple
- [B] Zebra
🔹 Sort Attributes
Common attributes used with <xsl:sort>:
- select: Specifies which node to sort by
- data-type: "text" (default) or "number"
- order: "ascending" (default) or "descending"
- case-order: "upper-first" or "lower-first"
<xsl:sort select="price"
data-type="number"
order="descending"/>💡 Key Points:
- Always use inside <xsl:for-each> or <xsl:apply-templates>
-
Use
data-type="number"for numerical sorting - Default order is ascending (A-Z, 0-9)
- Can sort by multiple criteria using multiple <xsl:sort> elements
- Sort happens before the loop processes nodes