MARC::Record(3) User Contributed Perl Documentation MARC::Record(3)NAMEMARC::Record - Perl extension for handling MARC records
VERSION
Version 2.0.0
DESCRIPTION
Module for handling MARC records as objects. The file-handling stuff
is in MARC::File::*.
ERROR HANDLING
Any errors generated are stored in $MARC::Record::ERROR. Warnings are
kept with the record and accessible in the "warnings()" method.
CONSTRUCTORSnew()
Base constructor for the class. It just returns a completely empty
record. To get real data, you'll need to populate it with fields, or
use one of the MARC::File::* modules to read from a file.
new_from_usmarc( $marcblob [, \&filter_func($tagno,$tagdata)] )
This is a wrapper around "MARC::File::USMARC::decode()" for
compatibility with older versions of MARC::Record.
The "wanted_func()" is optional. See MARC::File::USMARC::decode for
details.
COMMON FIELD RETRIEVAL METHODS
Following are a number of convenience methods for commonly-retrieved
data fields. Please note that they each return strings, not
MARC::Field objects. They return empty strings if the appropriate
field or subfield is not found. This is as opposed to the
"field()"/"subfield()" methods which return "undef" if something's not
found. My assumption is that these methods are used for quick & dirty
reports and you don't want to mess around with noting if something is
undef.
Also note that no punctuation cleanup is done. If the 245a is
"Programming Perl / ", then that's what you'll get back, rather than
"Programming Perl".
title()
Returns the title from the 245 tag.
title_proper()
Returns the title proper from the 245 tag, subfields a, n and p.
author()
Returns the author from the 100, 110 or 111 tag.
edition()
Returns the edition from the 250 tag, subfield a.
publication_date()
Returns the publication date from the 260 tag, subfield c.
FIELD & SUBFIELD ACCESS METHODSfields()
Returns a list of all the fields in the record. The list contains a
MARC::Field object for each field in the record.
field( tagspec(s) )
Returns a list of tags that match the field specifier, or an empty list
if nothing matched. In scalar context, returns the first matching tag,
or undef if nothing matched.
The field specifier can be a simple number (i.e. "245"), or use the "."
notation of wildcarding (i.e. subject tags are "6..").
subfield( $tag, $subfield )
Shortcut method for getting just a subfield for a tag. These are
equivalent:
my $title = $marc->field('245')->subfield("a");
my $title = $marc->subfield('245',"a");
If either the field or subfield can't be found, "undef" is returned.
append_fields( @fields )
Appends the field specified by $field to the end of the record.
@fields need to be MARC::Field objects.
my $field = MARC::Field->new('590','','','a' => 'My local note.');
$record->append_fields($field);
Returns the number of fields appended.
insert_fields_before( $before_field, @new_fields )
Inserts the field specified by $new_field before the field
$before_field. Returns the number of fields inserted, or undef on
failures. Both $before_field and all @new_fields need to be
MARC::Field objects. If they are not an exception will be thrown.
my $before_field = $record->field('260');
my $new_field = MARC::Field->new('250','','','a' => '2nd ed.');
$record->insert_fields_before($before_field,$new_field);
insert_fields_after( $after_field, @new_fields )
Identical to "insert_fields_before()", but fields are added after
$after_field. Remember, $after_field and any new fields must be valid
MARC::Field objects or else an exception will be thrown.
insert_fields_ordered( @new_fields )
Will insert fields in strictly numerical order. So a 008 will be filed
after a 001 field. See "insert_grouped_field()" for an additional
ordering.
insert_grouped_field( $field )
Will insert the specified MARC::Field object into the record in grouped
order and return true (1) on success, and false (undef) on failure.
my $field = MARC::Field->new( '510', 'Indexed by Google.' );
$record->insert_grouped_field( $field );
For example, if a '650' field is inserted with "insert_grouped_field()"
it will be inserted at the end of the 6XX group of tags. After
discussion most people wanted the ability to add a new field to the end
of the hundred group where it belonged. The reason is that according to
the MARC format, fields within a record are supposed to be grouped by
block (hundred groups). This means that fields may not necessarily be
in tag order.
delete_field( $field )
Deletes a field from the record.
The field must have been retrieved from the record using the "field()"
method. For example, to delete a 526 tag if it exists:
my $tag526 = $marc->field( "526" );
if ( $tag526 ) {
$marc->delete_field( $tag526 );
}
"delete_field()" returns the number of fields that were deleted. This
shouldn't be 0 unless you didn't get the tag properly.
as_usmarc()
This is a wrapper around "MARC::File::USMARC::encode()" for
compatibility with older versions of MARC::Record.
as_formatted()
Returns a pretty string for printing in a MARC dump.
leader()
Returns the leader for the record. Sets the leader if text is defined.
No error checking is done on the validity of the leader.
encoding()
A method for getting/setting the encoding for a record. The encoding
for a record is determined by position 09 in the leader, which is blank
for MARC-8 encoding, and 'a' for UCS/Unicode. encoding() will return a
string, either 'MARC-8' or 'UTF-8' appropriately.
If you want to set the encoding for a MARC::Record object you can use
the string values:
$record->encoding( 'UTF-8' );
NOTE: MARC::Record objects created from scratch have an a default
encoding of MARC-8, which has been the standard for years...but many
online catlogs and record vendors are migrating to UTF-8.
WARNING: you should be sure your record really does contain valid UTF-8
data when you manually set the encoding.
set_leader_lengths( $reclen, $baseaddr )
Internal function for updating the leader's length and base address.
clone()
The "clone()" method makes a copy of an existing MARC record and
returns the new version. Note that you cannot just say:
my $newmarc = $oldmarc;
This just makes a copy of the reference, not a new object. You must
use the "clone()" method like so:
my $newmarc = $oldmarc->clone;
You can also specify field specs to filter down only a certain subset
of fields. For instance, if you only wanted the title and ISBN tags
from a record, you could do this:
my $small_marc = $marc->clone( 245, '020' );
The order of the fields is preserved as it was in the original record.
warnings()
Returns the warnings (as a list) that were created when the record was
read. These are things like "Invalid indicators converted to blanks".
my @warnings = $record->warnings();
The warnings are items that you might be interested in, or might not.
It depends on how stringently you're checking data. If you're doing
some grunt data analysis, you probably don't care.
A side effect of calling warnings() is that the warning buffer will be
cleared.
add_fields()
"add_fields()" is now deprecated, and users are encouraged to use
"append_fields()", "insert_fields_after()", and
"insert_fields_before()" since they do what you want probably. It is
still here though, for backwards compatability.
"add_fields()" adds MARC::Field objects to the end of the list.
Returns the number of fields added, or "undef" if there was an error.
There are three ways of calling "add_fields()" to add data to the
record.
1 Create a MARC::Field object and add it
my $author = MARC::Field->new(
100, "1", " ", a => "Arnosky, Jim."
);
$marc->add_fields( $author );
2 Add the data fields directly, and let "add_fields()" take care of the
objectifying.
$marc->add_fields(
245, "1", "0",
a => "Raccoons and ripe corn /",
c => "Jim Arnosky.",
);
3 Same as #2 above, but pass multiple fields of data in anonymous lists
$marc->add_fields(
[ 250, " ", " ", a => "1st ed." ],
[ 650, "1", " ", a => "Raccoons." ],
);
DESIGN NOTES
A brief discussion of why MARC::Record is done the way it is:
· It's built for quick prototyping
One of the areas Perl excels is in allowing the programmer to
create easy solutions quickly. MARC::Record is designed along
those same lines. You want a program to dump all the 6XX tags in a
file? MARC::Record is your friend.
· It's built for extensibility
Currently, I'm using MARC::Record for analyzing bibliographic data,
but who knows what might happen in the future? MARC::Record needs
to be just as adept at authority data, too.
· It's designed around accessor methods
I use method calls everywhere, and I expect calling programs to do
the same, rather than accessing internal data directly. If you
access an object's hash fields on your own, future releases may
break your code.
· It's not built for speed
One of the tradeoffs in using accessor methods is some overhead in
the method calls. Is this slow? I don't know, I haven't measured.
I would suggest that if you're a cycle junkie that you use
Benchmark.pm to check to see where your bottlenecks are, and then
decide if MARC::Record is for you.
RELATED MODULES
MARC::Field, MARC::Batch, MARC::File::XML, MARC::Charset, MARC::Lint
SEE ALSO
· perl4lib (<http://www.rice.edu/perl4lib/>)
A mailing list devoted to the use of Perl in libraries.
· Library Of Congress MARC pages (<http://www.loc.gov/marc/>)
The definitive source for all things MARC.
· Understanding MARC Bibliographic (<http://lcweb.loc.gov/marc/umb/>)
Online version of the free booklet. An excellent overview of the
MARC format. Essential.
· Tag Of The Month (<http://www.tagofthemonth.com/>)
Follett Software Company's (<http://www.fsc.follett.com/>) monthly
discussion of various MARC tags.
TODO
· Incorporate MARC.pm in the distribution.
Combine MARC.pm and MARC::* into one distribution.
· Podify MARC.pm
· Allow regexes across the entire tag
Imagine something like this:
my @sears_headings = $marc->tag_grep( qr/Sears/ );
(from Mike O'Regan)
· Insert a field in an arbitrary place in the record
· Modifying an existing field
BUGS, WISHES AND CORRESPONDENCE
Please feel free to email me at "<mrylander@gmail.com>". I'm glad to
help as best I can, and I'm always interested in bugs, suggestions and
patches.
An excellent place to look for information, and get quick help, is from
the perl4lib mailing list. See <http://perl4lib.perl.org> for more
information about this list, and other helpful MARC information.
The MARC::Record development team uses the RT bug tracking system at
<http://rt.cpan.org>. If your email is about a bug or suggestion,
please report it through the RT system. This is a huge help for the
team, and you'll be notified of progress as things get fixed or
updated. If you prefer not to use the website, you can send your bug
to "<bug-MARC-Record@rt.cpan.org>"
IDEAS
Ideas are things that have been considered, but nobody's actually asked
for.
· Create multiple output formats.
These could be ASCII or MarcMaker.
LICENSE
This code may be distributed under the same terms as Perl itself.
Please note that these modules are not products of or supported by the
employers of the various contributors to the code.
AUTHOR
Andy Lester, "<andy@petdance.com>"
perl v5.14.1 2007-01-25 MARC::Record(3)
