sending marc records into a script that uses MARC::Batch

[John E Guillory]

Hello,
Two questions please:


1.      I've written a script that opens a marc file for reading using this 
syntax:

$file = $ARGV[0];
$batch = MARC::Batch->new('USMARC',$file);

It then loops thru the records using this syntax:
while ( $record = $batch->next()) {
         .....check position 6, 7 of leader and position 23 of 008 and make 
some changes
}

This works great. However, instead of accessing the file this way, I want to 
pipe the output of a previously run marc dump command directly into this script 
via the pipe.
I understand that this can be done using this syntax:    while ($line 
=<STDIN>){ ...}, but I don't understand how to use that STDIN with 
"MARC::Batch->new('USMARC',$file);"    This does not work:    $batch = 
MARC::Batch->new('USMARC',<STDIN>);


2.      My current script successfully reads and processes a marc file of over 
5 gigs!....but exits entirely on record 160,585 with the error from 
MARC::Batch, "Can't call method "as_string" on an undefined value at 
./marc_batch.pl".  Documentation on using MARC::Batch says that to tell it to 
continue processing even when errors are encountered one should use 
strict_off(), then print/report warnings at the bottom of the script. I don't 
think my particular error is being handled by the strict_off() setting. Doesn't 
anybody know what causes/how to fix "Can't call method as_string?" error? Full 
script below-it's pretty short, thanks to MARC::Batch.

Thanks for ensights!


use MARC::Batch;

$file = $ARGV[0];
chomp($file);

$batch = MARC::Batch->new('USMARC',$file);
$batch->strict_off();    # otherwise script exits when encounters errors

open(OUT,'>new_marc');

while ( $record = $batch->next()) {
    $leader                = $record->leader();
    $leader_pos_6          = substr($leader,6,1);
    $leader_pos_7          = substr($leader,7,1);

    $field                 = $record->field('008');
    $field_008             = $field->as_string();
    $field_008_position_23 = substr($field_008,23,1);

if ( ($leader_pos_6 eq "a") && ($leader_pos_7 eq "m") && 
($field_008_position_23 eq "o") || ($field_008_position_23 eq "s") ) {

       $control_num        = $record->field('001');
       $control_num        = $control_num->as_string();

       print "008 position 23: $field_008_position_23 \n";
       print "OLD leader: $leader \n";
       $old_leader = $leader;
       substr($leader,6,1) = 'm';
       print "NEW leader: $leader \n";

       print OUT $record->as_usmarc();
      print "$control_num|$old_leader|$leader|$field_008\n";

} else {  # not a match so just print this one unchanged...
       print OUT $record->as_usmarc();
}

}

# handles errors:
if (@warnings = $batch->warnings()) {
     print "\n Warnings detected: \n", @warnings;
}

close(OUT);
close(LOG);



John Guillory
Louisiana Library Network
225.578.3758