Valid XML and XML::Simple

mrguy123 has asked for the wisdom of the Perl Monks concerning the following question:

Hi monks,
I have been using the Perl Module XML::Simple quite a lot recently to parse XML and to test if XML is valid and well formed. Everything works great except for one problem.
Sometimes the XML I need to parse has ":" inside the tags, according to certain namespaces. For example

<person>
    <person:name>Joe</person:name>
    <person:job>programmer</person:job>
</person>
[download]

This is not valid XML according to W3C standards. If you save this as an XML file, and try to open it, you get an error. Also, if you go to http://www.w3schools.com/dom/dom_validate.asp and try to validate the XML, you get this error: "reference to undeclared namespace 'person'". My problem is that XML::Simple does not consider this XML invalid. For example, this code does not return an error:

#!/exlibris/metalib/m4_b/product/bin/perl
use strict;
use XML::Simple;

my $source_code =
"<person>
  <person:name>Joe</person:name>
  <person:job>programmer</person:job>
</person>";

my $xs = new XML::Simple();
my $hash;
##This should return an error!!
eval {$hash = $xs->XMLin($source_code)};
if ($@){
    print "$@";
    exit(0);
}
[download]

Since I am now working on a project to transform invalid XML to valid XML, and am also using a C XML parser that returns an error for this sort of XML, I have a problem. I know how to make the XML valid, but I also want XML::Simple to fail if the XML is invalid. Does anyone have any ideas what to do?
Thanks,
Guy

---A truth that's told with bad intent beats all the lies you can invent
Update: Fixed typo XML::simple -> XML::Simple

Update 2: Added an example from w3schools

Comment on Valid XML and XML::Simple Select or Download Code

Replies are listed 'Best First'.
Re: Valid XML and XML::Simple by GrandFather (Saint) on Oct 28, 2007 at 09:41 UTC
Where does w3c say that that is not valid XML? The XML spec in part says: [4] NameChar ::= Letter \| Digit \| '.' \| '-' \| '_' \| ':' \| CombiningChar \| Extender [5] Name ::= (Letter \| '_' \| ':') (NameChar)* and: The Namespaces in XML Recommendation XML Names assigns a meaning to names containing colon characters. Therefore, authors should not use the colon in XML names except for namespace purposes, but XML processors must accept the colon as a name character. which makes it pretty clear that colons not only are allowed, but must be accepted by XML processors. Perl is environmentally friendly - it saves trees	[reply]
Re^2: Valid XML and XML::Simple by mrguy123 (Hermit) on Oct 28, 2007 at 09:54 UTC
Hi, I'm assuming this is not black and white, but the fact is that if you save my example as an XML file, and try to open it, you get an error. It also fails when I try to parse it in "C".	[reply]
Re^3: Valid XML and XML::Simple by erroneousBollock (Curate) on Oct 28, 2007 at 13:06 UTC
The `foo:thing` syntax relates to namespaces. An XML parser must accept such syntax (here the node is a 'thing' in the 'foo' namespace). The document should be considered invalid because the 'person' namespace has not been declared at the top of the XML document. However, XML::Simple is (as it's name implies) a simplistic approach to parsing XML... it's not exactly a strict parser. It may or may not give you a warning about a missing 'prefix'. Use a more compliant parser such as XML::Parser (directly), XML::Twig or XML::LibXML. -David	[reply] [d/l]
Re^2: Valid XML and XML::Simple by mrguy123 (Hermit) on Oct 28, 2007 at 10:10 UTC
Hi again I added this in the decription: if you try to validate this XML in the w3schools page (http://www.w3schools.com/dom/dom_validate.asp) you get an error	[reply]
Re: Valid XML and XML::Simple by pKai (Priest) on Oct 28, 2007 at 12:24 UTC
I can confirm your symptom (i.e. "no error") when I force XML::Simple to use XML::Parser as its parser. Maybe your configuration uses XML::Parser as its default? Consult the "ENVIRONMENT" section in XML::Simple's documentation. If I let XML::Simple use XML::SAX as parser (which is my default, since it is installed), I get `Undeclared prefix: person at E:/perl/site/lib/XML/NamespaceSupport.pm +line 298.` [download] Which is "somewhat" similar to the message Anonymous Monk reports in the first reply in this thread (but who -- judging from his message -- uses some other parser).	[reply] [d/l]
Re^2: Valid XML and XML::Simple by mrguy123 (Hermit) on Oct 28, 2007 at 13:57 UTC
Thanks for the tip. I am trying to force XML::SAX, but am getting this error `Can't locate object method "new" via package "XML::SAX" at /exlibris/p +roduct/perl-5.8.7/lib/site_perl/5.8.7/XML/SAX/ParserFactory.pm line 4 +3.` [download] I will keep working on it	[reply] [d/l]
Re^3: Valid XML and XML::Simple by Jim (Curate) on Oct 29, 2007 at 00:33 UTC
From http://search.cpan.org/dist/XML-Simple/lib/XML/Simple.pm#Caveats: Names in XML must begin with a letter. The remaining characters may be letters, digits, hyphens (-), underscores (_) or full stops (.). It is also allowable to include one colon (:) in an element name but this should only be used when working with namespaces (XML::Simple can only usefully work with namespaces when teamed with a SAX Parser). From http://search.cpan.org/dist/XML-Simple/lib/XML/Simple.pm#SEE_ALSO: To generate documents with namespaces, XML::NamespaceSupport is required. Jim	[reply]
Re^3: Valid XML and XML::Simple by Anonymous Monk on Oct 28, 2007 at 22:41 UTC
`perldoc XML::SAx NAME XML::SAX - Simple API for XML SYNOPSIS use XML::SAX; # get a list of known parsers my $parsers = XML::SAX->parsers(); # add/update a parser XML::SAX->add_parser(q(XML::SAX::PurePerl)); # remove parser XML::SAX->remove_parser(q(XML::SAX::Foodelberry)); # save parsers XML::SAX->save_parsers();` [download]	[reply] [d/l]
Re: Valid XML and XML::Simple by Anonymous Monk on Oct 28, 2007 at 09:32 UTC
Check your vision `Can't locate object method "new" via package "XML::simple" (perhaps you forgot to load "XML::simple"?` If I fix that, I get `unbound prefix at line 2, column 3, byte 11` [download]	[reply] [d/l] [select]
Re^2: Valid XML and XML::Simple by mrguy123 (Hermit) on Oct 28, 2007 at 09:51 UTC
Sorry, it's supposed to be XML::Simple	[reply]
Re^3: Valid XML and XML::Simple by Anonymous Monk on Oct 28, 2007 at 12:06 UTC
`XML Parsing Error: prefix not bound to a namespace Line Number 2, Column 3: <person:name>Joe</person:name> --^` [download]	[reply] [d/l]
Re^3: Valid XML and XML::Simple by Anonymous Monk on Oct 28, 2007 at 12:00 UTC
Keep reading! If I fix that, I get `unbound prefix at line 2, column 3, byte 11` [download]	[reply] [d/l]


Welcome to the Monastery
	PerlMonks