prune xml of empty elements

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

I would like to use a CPAN module to clean my XML of any empty tags. Ie., given:

<note>
  <to>
    <person>Satan</person>
  </to>
  <from via="postcard" russia="with love">moneypenny</from>
  <heading></heading>
  <body></body>
</note>
[download]

I would like to see body and heading elements stripped out and the xml with only content-laden elements in it.

The mantra of every experienced web application developer is the same: thou shalt separate business logic from display. Ironically, almost all template engines allow violation of this separation principle, which is the very impetus for HTML template engine development.

-- Terence Parr, "Enforcing Strict Model View Separation in Template Engines"

Comment on prune xml of empty elements Download Code

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Re: prune xml of empty elements by toolic (Bishop) on Jul 14, 2011 at 17:11 UTC
XML::Twig can prune out all elements which have no text content: `use warnings; use strict; use XML::Twig; my $str = <<EOF; <note> <to> <person>Satan</person> </to> <from via="postcard" russia="with love">moneypenny</from> <heading></heading> <body></body> </note> EOF my $t = XML::Twig->new( pretty_print => 'indented', twig_handlers => { _all_ => sub { $_->delete() unless $_->text() } + } ); $t->parse($str); $t->print(); __END__ <note> <to> <person>Satan</person> </to> <from russia="with love" via="postcard">moneypenny</from> </note>` [download]	[reply] [d/l]
Re^2: prune xml of empty elements by Anonymous Monk on Jul 15, 2011 at 08:52 UTC
Updated based on this clarification #!/usr/bin/perl -- use warnings; use strict; use XML::Twig; my $str = <<'EOF'; <note> <to> <person>Satan</person> </to> <from via="postcard" russia="with love">moneypenny</from> <heading></heading> <body></body> <fudge a="body"></fudge> <fudge><a></a></fudge> <fudge><a body="good"></a></fudge> </note> EOF my $t = XML::Twig->new( pretty_print => 'indented', twig_handlers => { _all_ => sub { $_->delete() unless $_->has_child or $_->has_atts }, }, ); $t->parse($str); $t->print(); __END__ <note> <to> <person>Satan</person> </to> <from russia="with love" via="postcard">moneypenny</from> <fudge a="body"></fudge> <fudge> <a body="good"></a> </fudge> </note> [download]	[reply] [d/l]
Re: prune xml of empty elements by MidLifeXis (Monsignor) on Jul 14, 2011 at 17:48 UTC
Is a tag with only attributes considered empty? --MidLifeXis	[reply]
Re^2: prune xml of empty elements by metaperl (Curate) on Jul 14, 2011 at 20:27 UTC
I wouldnt say so, because attributes are actually child nodes with a single content item. The mantra of every experienced web application developer is the same: thou shalt separate business logic from display. Ironically, almost all template engines allow violation of this separation principle, which is the very impetus for HTML template engine development. -- Terence Parr, "Enforcing Strict Model View Separation in Template Engines"	[reply]
Re: prune xml of empty elements by Logicus (Initiate) on Jul 14, 2011 at 20:58 UTC
Easiest way to do this is : `use Modern::Perl; my $str = qq@ <note> <to> <person>Satan</person> </to> <from via="postcard" russia="with love">moneypenny</from> <heading></heading> <body></body> </note>@; $str =~ s@<(.*?)></\1>@@g; say $str;` [download] Output : `<note> <to> <person>Satan</person> </to> <from via="postcard" russia="with love">moneypenny</from> </note>` [download] No modules or parsing needed, just a simple one line regex.	[reply] [d/l] [select]
Re^2: prune xml of empty elements by chromatic (Archbishop) on Jul 15, 2011 at 06:39 UTC
No modules or parsing needed, just a simple one line regex. The only problem is that it doesn't prune every valid empty XML tag. If getting the correct result is important, use an XML parser.	[reply]
Re^2: prune xml of empty elements by happy.barney (Friar) on Jul 15, 2011 at 07:36 UTC
`$str =~ s@<(.?)/>@@g; 1 while $str =~ s@<(.?)>\s*</\1>@@g; $str =~ s@(?<=>)\s+(?=\n)@@g;` [download]	[reply] [d/l]
Re^2: prune xml of empty elements by jdporter (Paladin) on Jul 15, 2011 at 02:46 UTC
`s@<(.*?)></\1>@@g;` [download] I know one guy who writes regexes like that.	[reply] [d/l]


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