Try running the sample document through this transformation and you'll see that it doesn't output anything. In addition, if you don't want the processor to even walk the tree, you could override the built-in template for elements to do nothing, as shown here:. With this in place, the processor won't walk the tree, so it never makes it to the text nodes. If you run the sample document through this transformation, you'll see that it doesn't output anything either.
If you override this template, it means that you must be more precise about which nodes you want to process when calling xsl:apply-templates. A The xsl:include element makes it possible to include templates from one transformation into another. When you use xsl:include, it has to be a top-level element or, in other words, an immediate child of xsl:transform. Then you simply specify the location of the transformation you'd like to include using the href attribute, as illustrated here:.
Using xsl:include has no effect on the priority of the included templates. The templates included into the new transformation are treated as if they were defined inline. This is where xsl:import is different. The xsl:import element also allows you to include templates from one transformation into another. But when doing so, the imported templates automatically receive a lower precedence that is, a lower default priority than the templates in the including transformation see the earlier question on conflict resolution guidelines.
This is one of the main differences between xsl:include and xsl:import. Like xsl:include, xsl:import must also be a top-level element, and you specify the location of the transformation to be imported using the href attribute:.
XSLT also provides an xsl:apply-imports element similar to xsl:apply-templates , which allows you to process a set of nodes against the imported templates only. This facilitates overriding templates like you would override a method in object-oriented code. For example, consider the example in Figure 4 which overrides the employee template with additional details.
In this example, employee. Inside the employee template, it first calls xsl:apply-imports to process the imported employee template shown in global. The output from running employee. A XSLT provides an if statement xsl:if , but an else clause doesn't come with it. The xsl:if statement takes a Boolean expression in its test attribute, as shown here:.
If the test expression evaluates to true, the content within the xsl:if element is instantiated and processed. If you need an else clause, you have to use a different construct called xsl:choose, which is similar to a switch statement. The xsl:choose statement allows you to specify multiple test expressions, and the first one that evaluates to true starting from the top is instantiated and processed:. The xsl:choose also allows you to have an xsl:otherwise statement, which is instantiated if none of the test expressions evaluate to true.
I can't count the number of times I've started writing an xsl:if statement only to realize that I also needed an else clause, which forces me to start over using xsl:choose. So every time you start using xsl:if, ask yourself if you also need an else. If so, what options does it provide? It's a top-level element that should be an immediate child of xsl:transformation. The xsl:output element provides a wide range of options that control how the result tree is serialized. The following shows the syntax for xsl:output:.
As the XSLT processor runs a transformation, it builds a temporary result tree consisting of what's written to the output, either through static text within a template or through explicit calls to xsl:value-of. Then, the processor serializes the result tree to the output stream. Using xsl:output, you can influence how the XSLT processor performs this final step. The HTML output method, on the other hand, allows the processor to make several adjustments to the output in order to produce friendlier HTML documents.
For example, empty elements in HTML usually don't have end tags, and script and style tags don't require escape characters. These adjustments make it possible to produce HTML that will be easier to handle for most browsers. The text output method simply outputs all of the text nodes in the result document without any surrounding markup whatsoever.
If you don't specify the output method, the processor will automatically select one based on the temporary result tree. If the root element is named "html" case insensitive , it chooses the HTML output method; otherwise it defaults to the XML output method.
To change the default, you need to specify exactly which output method you want to use via xsl:output, as shown here:. You can also specify the version for the output method in use. The default version for XML is 1. For example, the following xsl:output element specifies that the output should use HTML 3.
You can also specify which character encoding you'd like the processor to use during serialization. This setting hints to the processor how it should transform the character stream into a byte stream. Although XSLT processors typically follow this hint, they're not required to do so.
The encoding indicated in the transformation can be overidden by the processor or certain APIs, which often leads to confusion. Perhaps worth adding that the quotation marks are needed because the test makes perfect sense without them: in that case, however, it asks whether the value of a Count child element is not-equal to the value of some A child element of an N child element.
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Visit chat. Linked 3. Related XSL has a collection of templates with certain conditions, which produces some control over the transformation. Templates do three main things. The first thing is matching a class of nodes which holds an XSLT pattern. If the templates match any of the nodes, then the processor picks one.
The second is a priority, and the last is to specify the structure. It is made mandatory unless it has a name attribute. In layman terms, we can say that an attribute is a pattern that defines which nodes to have and what attributes to apply to them. The match attribute includes a pattern expression, and it is used in a different process. The match keyword makes use of a pattern in an XSLT stylesheet, and it is an Xpath expression where the matching is made with the current node and also recursively traverse down the node in the tree to match additional templates.
All these templates are applied to the nodes of the input document, and when matches are made, the templates give out the desired output.
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