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Re: XPath with node names and attributes...

by thunders (Priest)
on Oct 16, 2009 at 16:56 UTC ( #801595=note: print w/replies, xml ) Need Help??


in reply to XPath with node names and attributes...

Perhaps It would help if you provide some example code and xml that demonstrates the problem you are having.
  • Comment on Re: XPath with node names and attributes...

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Re^2: XPath with node names and attributes...
by biswanath_c (Beadle) on Oct 16, 2009 at 17:33 UTC

    okay! here we go. I am just giving an example here that I tested and which demonstrates my problem:


    The XML:
    <root> <head> <node1 attr1="Node1 Attribute"> Node1 Value </node1> </head> </root>


    The PERL script that tries to read the attribute:

    use XML::LibXML; $inp = $ARGV[0]; # create object my $parser = XML::LibXML->new(); # read input XML file my $inp_tree = $parser->parse_file($inp); my $inp_root = $inp_tree->getDocumentElement; my $root_text = $inp_root->toString(); $rule_source = "head/node1@attr1"; my @inp_search_nodes = $inp_root->findnodes($rule_source); my $inp_search_results = scalar @inp_search_nodes; if ( 0 == $inp_search_results ) { print "XPath $rule_source not found! \n"; } else { my $path_text = $inp_search_nodes[ 0 ]->findvalue("."); print "Xpath ->: $path_text\n"; my $val = $inp_search_nodes[ 0 ]->textContent(); + print "Value of XPath $rule_source : $val \n"; }

    If i search for XPath head/node1@attr1 , the code works fine and fetches the value of the node.

    If i use XPath XPath /head/node1@attr1 , the program gives the error :
     "/head/node1 not found!"

    If i use the Xpath, i get this error:
     Invalid expression

    If I use the XPath "/head/node1/@attr1", I get this error:
     Invalid expression


      Didn't have a chance to test your example, but I think this is the problem:

      $rule_source = "head/node1@attr1";

      Perl thinks you want to insert the contents of an array called @attr1 into the string because you used double quotes. Since there is no such array your $rule_source ends up with just "head/node1". Either escape the '@' or use a single quoted string as in the examples below:

      $rule_source = "head/node1\@attr1"; # or $rule_source = 'head/node1@attr1';

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