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Preserving newlines with Web::Scraper

by nysus (Parson)
on Dec 25, 2018 at 11:12 UTC ( #1227690=perlquestion: print w/replies, xml ) Need Help??

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

I'm using Web::Scraper module to scrape text. Given following HTML:

<p class="myClass">Blah Blah Blah </p>

Note the newlines in the paragraph. I'm trying to preserve the whitespace (newlines) when scraping with this line:

process '//p[contains(@class, "myClass")]', 'paragraph' => 'TEXT +',

This works but without newlines. I tried RAW instead of TEXT but still have the problem. I seem to remember there being a third option but I can't remember what it is. Thanks.

$PM = "Perl Monk's";
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Re: Preserving newlines with Web::Scraper
by haukex (Bishop) on Dec 25, 2018 at 11:35 UTC

    It seems that Web::Scraper uses HTML::TreeBuilder::XPath, and HTML::TreeBuilder has an no_space_compacting option that is disabled by default, causing that module to do s/[\n\r\f\t ]+/ /g by default. At the moment I don't see a way to set arbitrary options on the parser via Web::Scraper, this is probably worth opening an issue for.

    Two workarounds I see at the moment: replacing Web::Scraper with Web::Scraper::LibXML works for me:

    use warnings; use strict; use Data::Dump; use Web::Scraper::LibXML; my $scraper = scraper { process '//p[contains(@class, "myClass")]', 'paragraph' => 'TEXT'; }; dd $scraper->scrape(\<<'END_HTML'); <p class="myClass">Blah Blah Blah </p> END_HTML __END__ { paragraph => "Blah\n\nBlah\n\nBlah\n" }

    Or, monkey-patching Web::Scraper::build_tree:

    *Web::Scraper::build_tree = sub { my($self, $html) = @_; my $t = HTML::TreeBuilder::XPath->new; $t->store_comments(1) if ($t->can('store_comments')); $t->no_space_compacting(1); $t->ignore_unknown(0); $t->parse($html); $t->eof; $t; };

      OK, thanks for confirming the issue. You posted seconds before I posted my hack workaround. Using LibXML looks like the way to go, though. Thanks a lot!

      $PM = "Perl Monk's";
      $MCF = "Most Clueless Friar Abbot Bishop Pontiff Deacon Curate Priest Vicar";
      $nysus = $PM . ' ' . $MCF;
      Click here if you love Perl Monks

Re: Preserving newlines with Web::Scraper
by nysus (Parson) on Dec 25, 2018 at 11:38 UTC

    Dug through the source code and hacked Web::Scraper to add the following to line #118: $t->no_space_compacting(1)

    This changes the behavior of HTML::TreeBuilder module used by Web::Scraper to find the nodes in the HTML document. Maybe there is a better way, though?

    UPDATE: this comment was made shortly after first comment without seeing it so is duplicative.

    $PM = "Perl Monk's";
    $MCF = "Most Clueless Friar Abbot Bishop Pontiff Deacon Curate Priest Vicar";
    $nysus = $PM . ' ' . $MCF;
    Click here if you love Perl Monks

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