Visitor Factory class for the
Groovy scripting language.
Implement DOM or SAX visitors using the Groovy scripting language.
Usage Tips
- Imports: Imports can be added via the "imports" element. A number of classes are automatically imported:
org.smooks.support.DomUtilsBeanContextorg.w3c.dom.*- groovy.xml.dom.DOMCategory, groovy.xml.dom.DOMUtil, groovy.xml.DOMBuilder
- Visited Element: The visited element is available to the script through the variable "element". It is also available
under a variable name equal to the element name, but only if the element name contains alpha-numeric
characters only.
- Execute Before/After: By default, the script is executed on the visitAfter event. You can direct it to be
executed on the visitBefore by setting the "executeBefore" attribute to "true".
- Comment/CDATA Script Wrapping: If the script contains special XML characters, it can be wrapped in an XML
Comment or CDATA section. See example below.
Mixing SAX and DOM Models
When using the SAX filter, Groovy scripts can take advantage of the
DomModelCreator.
This is only
the case when the script is applied on the visitAfter event of the targeted element (i.e. executeBefore="false",
which is the default). If executeBefore is set to "true", the
DomModelCreator will not be utilized.
What this means is that you can use DOM utilities to process the targeted message fragment. The "element"
received by the Groovy script will be a DOM
Element. This makes Groovy scripting via the SAX filter
a lot easier, while at the same time maintaining the ability to process huge messages in a streamed fashion.
Notes:
- Only available in default mode i.e. when executeBefore equals "false". If executeBefore is configured
"true", this facility is not available and the Groovy script will only have access to the element
as a
Element.
- The DOM fragment must be explicitly writen to the result using "writeFragment". See example below.
- There is an obvious performance overhead incurred using this facility (DOM construction). That said, it can still
be used to process huge messages because of how the
DomModelCreator works for SAX.
Example Configuration
Take an XML message such as:
<shopping>
<category type="groceries">
<item>Chocolate</item>
<item>Coffee</item>
</category>
<category type="supplies">
<item>Paper</item>
<item quantity="4">Pens</item>
</category>
<category type="present">
<item when="Aug 10">Kathryn's Birthday</item>
</category>
</shopping>
Using Groovy, we want to modify the "supplies" category in the shopping list, adding 2 to the
quantity, where the item is "Pens". To do this, we write a simple little Groovy script and target
it at the <category> elements in the message. The script simple iterates over the <item> elements
in the category and increments the quantity by 2, where the category type is "supplies" and the item is "Pens":
<?xml version="1.0"?>
<smooks-resource-list xmlns="https://www.smooks.org/xsd/smooks-2.0.xsd" xmlns:g="https://www.smooks.org/xsd/smooks/groovy-2.0.xsd">
<!--
Use the SAX filter. Note how we can still process the fragment as a DOM, and write it out
to the result stream after processing.
-->
<params>
<param name="stream.filter.type">SAX</param>
</params>
<g:groovy executeOnElement="category">
<g:script>
<!--
use(DOMCategory) {
// modify supplies: we need an extra 2 pens
if (category.'@type' == 'supplies') {
category.item.each { item ->
if (item.text() == 'Pens') {
item['@quantity'] = item.'@quantity'.toInteger() + 2
}
}
}
}
// Must explicitly write the fragment to the result stream when
// using the SAX filter.
writeFragment(category);
-->
</g:script>
</g:groovy>
</smooks-resource-list>