[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.ruby

XML file processing using REXML (beginner's question

Ronald Fischer

7/12/2007 1:58:00 PM

Hello!

I try to understand REXML using the tutorial in

http://www.germane-software.com/software/rexml/docs/tut...

However, I have problems applying the path expressions to my
application.
Consider for example the following program, and in particular the last
line:

#!/usr/bin/ruby
require "rexml/document"
require 'pp'
source=<<ENDXML
<ns:toplevel>
<ns:request requestID="1">
<ns:application aid="demo-a">
</ns:application>
</ns:request>
<ns:request requestID="2">
<ns:application aid="demo-b">
</ns:application>
</ns:request>
</ns:toplevel>
ENDXML
doc=REXML::Document.new source
doc.elements.each("ns:toplevel/ns:request") { |element| puts
element.attributes["requestID"] }
root=doc.root
pp root.elements["ns:toplevel/ns:request[@requestID='2']"]

The program outputs

1
2
nil

that is, it finds the two elements "request" and correctly outputs their
attribute
requestID, but when I try to locate request number two with the path
expression

ns:toplevel/ns:request[@requestID='2']

it is not found. What am I doing wrong here?

Ronald
--
Ronald Fischer <ronald.fischer@venyon.com>
Phone: +49-89-452133-162
3 Answers

Todd Benson

7/12/2007 4:22:00 PM

0

On 7/12/07, Ronald Fischer <ronald.fischer@venyon.com> wrote:
> Hello!
>
> I try to understand REXML using the tutorial in
>
> http://www.germane-software.com/software/rexml/docs/tut...
>
> However, I have problems applying the path expressions to my
> application.
> Consider for example the following program, and in particular the last
> line:
>
> #!/usr/bin/ruby
> require "rexml/document"
> require 'pp'
> source=<<ENDXML
> <ns:toplevel>
> <ns:request requestID="1">
> <ns:application aid="demo-a">
> </ns:application>
> </ns:request>
> <ns:request requestID="2">
> <ns:application aid="demo-b">
> </ns:application>
> </ns:request>
> </ns:toplevel>
> ENDXML
> doc=REXML::Document.new source
> doc.elements.each("ns:toplevel/ns:request") { |element| puts
> element.attributes["requestID"] }
> root=doc.root
> pp root.elements["ns:toplevel/ns:request[@requestID='2']"]
>
> The program outputs
>
> 1
> 2
> nil
>
> that is, it finds the two elements "request" and correctly outputs their
> attribute
> requestID, but when I try to locate request number two with the path
> expression
>
> ns:toplevel/ns:request[@requestID='2']
>
> it is not found. What am I doing wrong here?

Your root variable represents your ns:toplevel so, either of these
would return an object instead of nil ...

pp root.elements["ns:request[@requestID='2']"]
pp doc.elements["ns:toplevel/ns:request[@requestID='2']"]

Todd

Keith Fahlgren

7/12/2007 5:19:00 PM

0

On 7/12/07, Ronald Fischer <ronald.fischer@venyon.com> wrote:
> Hello!
>
> I try to understand REXML using the tutorial in

Hi,

You seem comfortable with XPath, so let me strongly encourage the
methods defined in the REXML::XPath class instead of the []-based
methods.

http://www.germane-software.com/software/XML/rexml/doc/classes/REXML/...

$ cat rbtalk.rb
#!/usr/bin/env ruby
require "rexml/document"
source=<<ENDXML
<ns:toplevel>
<ns:request requestID="1">
<ns:application aid="demo-a">
</ns:application>
</ns:request>
<ns:request requestID="2">
<ns:application aid="demo-b">
</ns:application>
</ns:request>
</ns:toplevel>
ENDXML
doc = REXML::Document.new source
REXML::XPath.each(doc, "/ns:toplevel/ns:request") {|element|
puts element.attributes["requestID"]
}
p REXML::XPath.match(doc, "/ns:toplevel/ns:request[@requestID='2']")


$ ruby ./rbtalk.rb
1
2
[<ns:request requestID='2'> ... </>]



HTH,
Keith

Ronald Fischer

7/13/2007 7:47:00 AM

0


> You seem comfortable with XPath, so let me strongly encourage the
> methods defined in the REXML::XPath class instead of the []-based
> methods.

> REXML::XPath.each(doc, "/ns:toplevel/ns:request") {|element|
> puts element.attributes["requestID"]
> }
> p REXML::XPath.match(doc, "/ns:toplevel/ns:request[@requestID='2']")

Thanks a lot for the suggestion!

(And also thanks to Todd Benson for pointing out my error).

Ronald