Generate Two Seperate XML Files by Walking DOM Tree and Using Attributes

Question

I need to segregate xml code into two separate files by using the optional attribute values. I prefer to use the XML::LibXML DOM methods, using Perl.

Sample XML code excerpt:
...
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>
    <Address string="ops">ops.zla</Address>
    <Address string="spt">spt.zla</Address>
    <Port>77777</Port>
  </PrimaryConnection>
  <SecondaryConnection string="ops">
    <Address>abc.zla</Address>
    <Port>77777</Port>
  </SecondaryConnection>
</LocalJMS>

The desirable resulting two final xml files would be:

1.) OPS file:
...
 <LocalJMS>
   <Name>ZLAT</Name>
   <PrimaryConnection>
     <Address>ops.zla</Address>
     <Port>77777</Port>
   </PrimaryConnection>
   <SecondaryConnection>
     <Address>abc.zla</Address>
     <Port>77777</Port>
   </SecondaryConnection>
 </LocalJMS>

2.) SPT file:
...
 <LocalJMS>
   <Name>ZLAT</Name>
   <PrimaryConnection>
     <Address>spt.zla</Address>
     <Port>77777</Port>
   </PrimaryConnection>
 </LocalJMS>

I have no problem/issue removing the attributes prior to generating the two final xml files, nor do I have any issue with making a decision on a element with an attribute that has no child elements - I can handle that as far pumping the xml content to the correct final xml file when I walk the DOM tree and checking on the childnodes.

But the problem I'm encountering is when the attribute is defined within a child element (e.g. 'SecondaryConnection', which is a child of 'LocalJMS'). If I "walk" the DOM tree, I will first encounter the parent element 'LocalJMS', and I need some of it's children elements (e.g. 'Name', 'PrimaryConnection') to go to both final files, but then I only need the 'SecondaryConnection' element to go only to the OPS xml file (not the SPT file). [btw, the attribute is applicable to all child nodes, i.e. 'Address' & 'Port']

I'm looking for some ideas - maybe using parse_balanced_chunk or work from the deepest part of the originally xml file and work outwards, cycling thru each child node. I hate like heck to have to use traditional grep patterns etc and treat the xml file like a simple text file - I was hoping to take advantage of the DOM methods.

Answer 1

I suggest that you parse the original XML, and then for each value of the string attribute you can clone the whole document and remove all elements that have an attribute with any value for string different from the one required

It would look like this. I am sure you're able to alter the output to something more appropriate if necessary

use strict;
use warnings 'all';

use XML::LibXML;

my $dom = XML::LibXML->load_xml( location => 'sample.xml' );

for my $string ( qw/ ops spt / ) {

    print "\$string = $string\n\n";

    my $copy = $dom->cloneNode(1);

    for my $unwanted ( $copy->findnodes("//*[\@string != '$string']") ) {
        my $parent = $unwanted->parentNode;
        $parent->removeChild($unwanted);
    }

    print $copy, "\n\n---\n\n";
}

output

$string = ops

<?xml version="1.0"?>
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>
    <Address string="ops">ops.zla</Address>

    <Port>77777</Port>
  </PrimaryConnection>
  <SecondaryConnection string="ops">
    <Address>abc.zla</Address>
    <Port>77777</Port>
  </SecondaryConnection>
</LocalJMS>


---

$string = spt

<?xml version="1.0"?>
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>

    <Address string="spt">spt.zla</Address>
    <Port>77777</Port>
  </PrimaryConnection>

</LocalJMS>


---

[Finished in 0.8s]

Answer 2

It's not XML parsing like you wanted, but seems to work for your sample data. Tags with a string="filename" attribute goes only into only that file (where filename is uppercased), with the string attribute removed. And all other tags goes into all files:

my $input=join"",<DATA>;
my @string=$input=~/ string="(\w+)"/g;
for my $s (@string){
    my $output=$input;
    $output=~
      s{ (\s*) <(\w+)\s* ([^>]*?) string="(\w+)" (.*?</\2>) }
       { $4 eq $s ? "$1<$2$3$5" : ""                        }gsex;
    open my $FH, '>', uc($s) or die;
    print $FH $output;
    close($FH)
}
__DATA__
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>
    <Address string="ops">ops.zla</Address>
    <Address string="spt">spt.zla</Address>
    <Port>77777</Port>
  </PrimaryConnection>
  <SecondaryConnection string="ops">
    <Address>abc.zla</Address>
    <Port>77777</Port>
  </SecondaryConnection>
</LocalJMS>

Output:

$ cat OPS 
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>
    <Address>ops.zla</Address>
    <Port>77777</Port>
  </PrimaryConnection>
  <SecondaryConnection>
    <Address>abc.zla</Address>
    <Port>77777</Port>
  </SecondaryConnection>
</LocalJMS>

$ cat SPT
<LocalJMS>
  <Name>ZLAT</Name>
  <PrimaryConnection>
    <Address>spt.zla</Address>
    <Port>77777</Port>
  </PrimaryConnection>
</LocalJMS>