XSLT <choose> Element

The XSLT <xsl:choose> element allows you to compare a value against a range of possible values in your XML document.

This element is used in conjunction with the <xsl:when> and (optionally) <xsl:otherwise> elements to present different content depending on the outcome of each test.

<xsl:choose> Example

The Source File

Imagine we have an XML file containing different food items and their nutritional value - like this:

Code

<?xml version="1.0"?> <food_list> <food_item type="vegetable"> <name>Agar</name> <carbs_per_serving>81</carbs_per_serving> <fiber_per_serving>8</fiber_per_serving> <fat_per_serving>0.5</fat_per_serving> <kj_per_serving>1280</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Asparagus</name> <carbs_per_serving>1</carbs_per_serving> <fiber_per_serving>1</fiber_per_serving> <fat_per_serving>0</fat_per_serving> <kj_per_serving>40</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Cabbage</name> <carbs_per_serving>0</carbs_per_serving> <fiber_per_serving>1</fiber_per_serving> <fat_per_serving>0</fat_per_serving> <kj_per_serving>14</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Potato</name> <carbs_per_serving>21.5</carbs_per_serving> <fiber_per_serving>2</fiber_per_serving> <fat_per_serving>1</fat_per_serving> <kj_per_serving>460</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Pumpkin</name> <carbs_per_serving>6</carbs_per_serving> <fiber_per_serving>1</fiber_per_serving> <fat_per_serving>0.5</fat_per_serving> <kj_per_serving>150</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Yam</name> <carbs_per_serving>30.5</carbs_per_serving> <fiber_per_serving>2</fiber_per_serving> <fat_per_serving>0.5</fat_per_serving> <kj_per_serving>550</kj_per_serving> </food_item> <food_item type="vegetable"> <name>Zucchini</name> <carbs_per_serving>1.5</carbs_per_serving> <fiber_per_serving>1.5</fiber_per_serving> <fat_per_serving>0.5</fat_per_serving> <kj_per_serving>55</kj_per_serving> </food_item> <food_item type="seafood"> <name>Abalone</name> <carbs_per_serving>0</carbs_per_serving> <fiber_per_serving>0</fiber_per_serving> <fat_per_serving>1</fat_per_serving> <kj_per_serving>400</kj_per_serving> </food_item> <food_item type="seafood"> <name>Barramundi</name> <carbs_per_serving>0</carbs_per_serving> <fiber_per_serving>0</fiber_per_serving> <fat_per_serving>2</fat_per_serving> <kj_per_serving>390</kj_per_serving> </food_item> <food_item type="fruit"> <name>Apple</name> <carbs_per_serving>15</carbs_per_serving> <fiber_per_serving>2.5</fiber_per_serving> <fat_per_serving>0</fat_per_serving> <kj_per_serving>250</kj_per_serving> </food_item> <food_item type="fruit"> <name>Kiwi Fruit</name> <carbs_per_serving>7.5</carbs_per_serving> <fiber_per_serving>2.5</fiber_per_serving> <fat_per_serving>0</fat_per_serving> <kj_per_serving>150</kj_per_serving> </food_item> <food_item type="grain"> <name>Oatbran</name> <carbs_per_serving>62</carbs_per_serving> <fiber_per_serving>14</fiber_per_serving> <fat_per_serving>7</fat_per_serving> <kj_per_serving>1400</kj_per_serving> </food_item> <food_item type="grain"> <name>Wheatgerm</name> <carbs_per_serving>1.5</carbs_per_serving> <fiber_per_serving>1</fiber_per_serving> <fat_per_serving>0.5</fat_per_serving> <kj_per_serving>70</kj_per_serving> </food_item> </food_list>

The Requirement

Now, imagine if we want to present the contents of our XML file in a table and highlight the rows a different color depending on the type of food it is - something like this:

The Solution

We could do this using the following XSL file. In this file, we are checking the type attribute of the <food_item> element. We can find the value of the attribute by typing it's name with a @. If the value is "grain" we specify one color. If it's "vegetable" we specify another. If it's neither of these, we specify a default color using <xsl:otherwise>.

Code

<?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/"> <xsl:apply-templates/> </xsl:template> <xsl:template match="food_list"> <table> <tr style="background-color:#ccff00"> <th>Food Item</th> <th>Carbs (g)</th> <th>Fiber (g)</th> <th>Fat (g)</th> <th>Energy (kj)</th> </tr> <xsl:for-each select="food_item"> <xsl:choose> <xsl:when test="@type = 'grain'"> <tr style="background-color:#cccc00"> <td><xsl:value-of select="name"/></td> <td><xsl:value-of select="carbs_per_serving"/></td> <td><xsl:value-of select="fiber_per_serving"/></td> <td><xsl:value-of select="fat_per_serving"/></td> <td><xsl:value-of select="kj_per_serving"/></td> </tr> </xsl:when> <xsl:when test="@type = 'vegetable'"> <tr style="background-color:#00cc00"> <td><xsl:value-of select="name"/></td> <td><xsl:value-of select="carbs_per_serving"/></td> <td><xsl:value-of select="fiber_per_serving"/></td> <td><xsl:value-of select="fat_per_serving"/></td> <td><xsl:value-of select="kj_per_serving"/></td> </tr> </xsl:when> <xsl:otherwise> <tr style="background-color:#cccccc"> <td><xsl:value-of select="name"/></td> <td><xsl:value-of select="carbs_per_serving"/></td> <td><xsl:value-of select="fiber_per_serving"/></td> <td><xsl:value-of select="fat_per_serving"/></td> <td><xsl:value-of select="kj_per_serving"/></td> </tr> </xsl:otherwise> </xsl:choose> </xsl:for-each> </table> </xsl:template> </xsl:stylesheet>

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