RE: MARC.pm unblessed reference

[Bryan Baldus]

> -----Original Message-----
> From: Aaron Huber [mailto:[EMAIL PROTECTED] 
> Sent: Monday, November 21, 2005 10:33 PM
> To: perl4lib@perl.org
> Subject: MARC.pm unblessed reference
> 
> 
> Hi All,
> 
> I am a complete newbie to this and have been testing out  MARC.pm. 
> I'm trying to return just the ISBN values from a group of MARC
> records. It works fine when I specify the record number, but when I
> put it through the loop it returns the above error.

My recommendation would be that you try to switch from MARC.pm to the
MARC::Record distribution
(see a previous posting to this list
<http://www.nntp.perl.org/group/perl.perl4lib/2166>). 

Then the code below should accomplish what you want (though I have not
tested it as it appears in this message--see
<http://home.inwave.com/eija/fullrecscripts/Extraction/extractisbn.txt> for
the original version, for which you would need to also install my
MARC::BBMARC (from my website or MARC::Errorchecks from CPAN, which includes
that module)). In my modified version below, I extract only subfield 'a' of
the 020, and I clean the field to (hopefully) leave only the ISBN portion of
the field--removing any qualifiers. It should be easy enough to modify the
code to extract the entire 020 field as_string() and report it.

I hope this helps,
Bryan Baldus
[EMAIL PROTECTED]
[EMAIL PROTECTED]
http://home.inwave.com/eija

############################

#!perl

=head2

Extracts ISBN from file of MARC records.

=cut

###########################
### Initialize includes ###
### and basic needs     ###
###########################
use strict;
#MARC::Batch is installed as part of MARC::Record
use MARC::Batch;

#########################
### Start main program ##
#########################

my $inputfile= 'marc.dat';
#my $exportfile = 'out.dat';
#open(OUT, ">$exportfile") or die "Problem opening $exportfile, $!";

#initialize $batch as new MARC::Batch object
my $batch = MARC::Batch->new('USMARC', "$inputfile");
########## Start extraction #########

my $runningrecordcount=0;
#### Start while loop through records in file #####
while ( my $record = $batch->next() ) {
        $runningrecordcount++;

        #get control number for reporting
        #my $controlno = $record->field('001')->as_string() if
($record->field('001'));

        ### loop through each 020 field ###
        for my $field020 ( $record->field("020") ) {
                my $isbn = $field020->subfield('a') if
($field020->subfield('a'));

                if (defined ($isbn)) {
                        #remove any hyphens
                        $isbn =~ s/\-//g;
                        #remove nondigits
                        $isbn =~ s/^\D*(\d{9,12}[X\d])\b.*$/$1/;
                        
                        # Now report it
                        print $runningrecordcount, ": ", $isbn, "\n";

                } # if isbn defined
        } # for
} # while

##########################
### Main program done.  ##
##########################

#####################
### END OF PROGRAM ##
#####################