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Re: sorting a file by a date:"YYYY-MM-DD" field with cmp

by ikegami (Patriarch)
on Jun 16, 2015 at 17:45 UTC ( #1130653=note: print w/replies, xml ) Need Help??


in reply to sorting a file by a date:"YYYY-MM-DD" field with cmp

In scalar context, the match operator and thus the bind operator returns whether a match was found or not. You want to evaluate the match in list context to get it to return the list of matches.

Fix:

my ($aDate) = $a =~ /\bdate:\s*"(\d{4}-\d{2}-\d{2})"/; my ($bDate) = $b =~ /\bdate:\s*"(\d{4}-\d{2}-\d{2})"/;

Also:

  • Added \b to avoid catching enddate.
  • Added \s* in case the JSON encoder decides to start adding whitespace.
  • Removed some superfluous backslashes.

Note: Will break if you get

  • { date:"\u0032015-05-01", content:"erwa" }
  • { foo:{date:"2014-05-01"}, date:"2015-05-01", content:"erwa" }
  • etc

For a reliable but slower solution, you can use

use JSON::XS qw( decode_json ); my @sorted = map { substr($_, 10) } sort map { decode_json($_)->{date} . $_ } @events;

As for the blank lines, just remove them first using

@events = grep /\S/, @events;

Update: Added to my answer.

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