<xsl:choose> Example

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:

 <?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>.

 <?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>