I would like to use Ruby and REXML to wrap an XML document and allow
access to the element nodes, attributes, and text. Essentially I need
an XML document builder loosely coupled from the document.
It seems like Ruby is powerful enough to code generate a class given an
XML document or build an object at run-time with the appropriate
accessors.
For instance:
order = XmlBuilder.new
order.add(“root”).add(“header”)
order.root.add(“body”)
order.body.add(“component”).attributes[“type”] = “metric”
order.write($stdout)
I’d also like to be able to plug-in input validation when assigning
values to elements and attributes.
Has anyone done this before?
Thanks.
Miles Monroe wrote:
I would like to use Ruby and REXML to wrap an XML document and allow
access to the element nodes, attributes, and text. Essentially I need
an XML document builder loosely coupled from the document.
It seems like Ruby is powerful enough to code generate a class given an
XML document or build an object at run-time with the appropriate
accessors.
For instance:
order = XmlBuilder.new
order.add(“root”).add(“header”)
order.root.add(“body”)
order.body.add(“component”).attributes[“type”] = “metric”
order.write($stdout)
I’d also like to be able to plug-in input validation when assigning
values to elements and attributes.
Has anyone done this before?
Thanks.
I found this blog entry on a XmlStringBuffer class in Ruby. I
understand using method_missing to create the element, but I’m not sure
how to closures would be implemented. Thanks.
http://www.beust.com/weblog/archives/000025.html
xml = XML.new
xml.html {
xml.head {
}
xml.body {
xml.table {
xml.tr {
xml.td({ “valign” => “top”}, “Content1”){
}
xml.td {
xml.append(“Content2”)
}
}
}
}
}
Miles Monroe wrote:
I would like to use Ruby and REXML to wrap an XML document and allow
access to the element nodes, attributes, and text. Essentially I need
an XML document builder loosely coupled from the document.
It seems like Ruby is powerful enough to code generate a class given an
XML document or build an object at run-time with the appropriate
accessors.
For instance:
order = XmlBuilder.new
[… example elided …]
Are you wanting to build a DOM object, or build a string containing XML
markup? If the later, Builder::XmlMarkup will do this. If the former,
it would be interesting to create a Builder with a similar API to
Buidler::XmlMarkup, but generated DOM trees instead of strings.
Or perhaps you are looking for something completely different.
XML Builder Link: http://builder.rubyforge.org/
–
– Jim W.
Hi Miles,
interesting idea, i did a quick (proof of concept) hack:
class Xmltree
attr_accessor :childs
attr_accessor :content
attr_accessor :attributes
def initialize
self.childs = []
self.attributes = {};
end
def method_missing meth, *args, &block
return attributes[args[0]] = args[1] if meth == :[]=
return attributes[args[0]] if meth == :[]
return self.content = args if meth == ‘=’.intern
unless child = childs.assoc(meth.to_s.chomp('='))
childs << child = [meth.to_s.chomp('='), Xmltree.new]
end
return child[1] if meth.to_s[-1] != ?=
child[1].content = args
end
def to_s
childs.map do |t, c|
“”"<#{t} #{c.attributes.map do |a, v|
“#{a}=”#{v}""
end.join(’ ')}>\n#{c}</#{t}>\n"""
end.join + content.to_s + (content ? “\n” : ‘’)
end
end
usage:
xml = Xmltree.new
xml.header.title = ‘this is a demo’
xml.body.component[‘type’] = ‘the answer’
xml.body.component = 42
puts xml
output:
this is a demo
42
-------------------------------------------------------------
cheers
Simon
Miles Monroe:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/116822
http://www.rubyquiz.com/quiz34.html
I found a couple links on source filters for Ruby.
I guess what I was proposing was just something like this:
/html/head/title << “Implicit XML Document”
/html/body/h1 << “Ruby source filters”
/html/body/h1[“class”] = “golden”
/html/body/table[“id”] = “QueryResults”
puts $_implicit_XML
Simon Kröger wrote:
Hi Miles,
interesting idea, i did a quick (proof of concept) hack:
class Xmltree
attr_accessor :childs
attr_accessor :content
attr_accessor :attributes
def initialize
self.childs = []
self.attributes = {};
end
def method_missing meth, *args, &block
return attributes[args[0]] = args[1] if meth == :[]=
return attributes[args[0]] if meth == :[]
return self.content = args if meth == ‘=’.intern
unless child = childs.assoc(meth.to_s.chomp('='))
childs << child = [meth.to_s.chomp('='), Xmltree.new]
end
return child[1] if meth.to_s[-1] != ?=
child[1].content = args
end
def to_s
childs.map do |t, c|
“”"<#{t} #{c.attributes.map do |a, v|
“#{a}=”#{v}""
end.join(’ ')}>\n#{c}</#{t}>\n"""
end.join + content.to_s + (content ? “\n” : ‘’)
end
end
usage:
xml = Xmltree.new
xml.header.title = ‘this is a demo’
xml.body.component[‘type’] = ‘the answer’
xml.body.component = 42
puts xml
output:
this is a demo
42
-------------------------------------------------------------
cheers
Simon
Miles Monroe:
Awesome! That is better than I ever imagined.
Back in my Perl days, I started creating a source filter to allow the
insertion of non-Perl XPath statements that worked on an implicit XML
document.
I used the source filter to first scan the code for naked XPath
statements and then built the XML document with the slightly-modified
XPath syntax. I converted the invalid non-Perl strings into valid Perl
in the source filter.
Likewise, is it possible to insert non-Ruby text in the main namespace
and then turn it into Ruby code before the rest of the script is parsed?
I guess I’m asking if it’s possible to implement a source filter in
Ruby.
Thanks.
Last time I was doing playing with XML, I wanted to be able to,
basically, add methods on to the nodes matching xpaths. It didn’t
seem to be very easy. I wondered at the time if some kind of
transform idea would work better.