Omit empty attributes with groovy DOMBuilder - dom

Question

Groovy's MarkupBuilder has an omitNullAttributes and an omitEmptyAttributes. But DOMBuilder doesn't. This is the code I have
>>> def xml = DOMBuilder.newInstance()
>>> def maybeEmpty = null
>>> println xml.foo(bar: maybeEmpty)
<foo bar=""/>
I want bar to be omitted if empty. I found a workaround in an answer to Groovy AntBuilder, omit conditional attributes... to findAll empty attributes and remove them. Since I have a complex DOM to be generated, I'm looking for other options.

Answer 1

I believe there is no built-in option for that, but if you need a DOMBuilder, you could subclass it and filter the attributes...
#groovy.transform.InheritConstructors
class DOMBuilderSubclass extends groovy.xml.DOMBuilder {
#Override
protected Object createNode(Object name, Map attributes) {
super.createNode name, attributes.findAll{it.value != null}
}
}
You might want to tune the construction as in standard DOMBuilder, this is just an example.
def factory = groovy.xml.FactorySupport.createDocumentBuilderFactory().newDocumentBuilder()
def builder = new DOMBuilderSubclass(factory)
println builder.foo(bar: null, baz: 1)
//<?xml version="1.0" encoding="UTF-8"?>
//<foo baz="1"/>
standard output as you said was...
println groovy.xml.DOMBuilder.newInstance().foo(bar: null, baz: 1)
//<?xml version="1.0" encoding="UTF-8"?>
//<foo bar="" baz="1"/>