Groovy系列：GPath

Posted 2021-02-27

//GPath can be used to easily query XML-based documents or even Object Graphs. 
//We start with looking at an XML GPath example.
 
//Let's load the Grails Pocast RSS Feed first.
println "new XmlSluper".center(75, '*')
def feed = new XmlSlurper().parse('http://hansamann.podhost.de/rss')
assert feed.getClass().name == 'groovy.util.slurpersupport.NodeChild'
 
 
//Like using XPath expressions, we can now navigate the tre
//This accesses the first iem element of the RSS channel:
println "Access to node content".center(75, '*')
println feed.channel.item[0].title
println feed.channel.item[0]['title']
 
 
//As in XPath, attributes are accessed with the @ syntax.
println "Access to attribute content".center(75, '*')
println feed.channel.item[0].enclosure[email protected] 
println feed.channel.item[0].enclosure['@url'] 
 
//Let's see how many podcasts whe have done so far. 
println "item element count".center(75, '*')
println feed.channel.item.size()
 
//We can iterate over all items with this
println "All titles below".center(75, '*')
feed.channel.item.each { item ->
    println item.title
}
 
//hier will ich die items nach Groovy Series filtern... 
//def groovySeries = feed.channel.item.findAll{ return (it.title.indexOf('Groovy Series')) ? true : false;} //wieso geht das nicht... println it.title geht
//println "Found ${groovySeries.size()}"
 
//playing with methods of GPathResult. NodeChild is an extension of GPathResult
assert feed.channel.item[0].enclosure[0].getClass().name == 'groovy.util.slurpersupport.NodeChild'
 
//to call the attributes method, we neet to macke sure that we are operating on a single Node, not a set
feed.channel.item[0].enclosure[0].attributes().each{println it} //works
try {
    feed.channel.item[0].enclosure.attributes().each{println it}
} catch (MissingMethodException e)
{
    assert feed.channel.item[0].enclosure.getClass().name == 'groovy.util.slurpersupport.NodeChildren'
    //above returns a NodeChildren object as it is a path expression for all enclosure tags of the first item tag!
}
 
//let's print all children of an item.
println "All children of item[0]".center(75, '*')
feed.channel.item[0].children().each { println it.name() } //will print tag names contained in item: title, description, author, pubDate, guid, link, enclosure
assert feed.channel.item[0].children().size() == 7
 
//Beispiel mit GPathResult->find / findAll
 
 
//evtl. xmlslurper dazu verwenden ein xml-doc zu veraendern??