MARC::Field(3pm)

1MARC::Field(3)        User Contributed Perl Documentation       MARC::Field(3)
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NAME

6       MARC::Field - Perl extension for handling MARC fields
7

SYNOPSIS

9         use MARC::Field;
10
11         my $field = MARC::Field->new( 245, '1', '0',
12              'a' => 'Raccoons and ripe corn / ',
13              'c' => 'Jim Arnosky.'
14         );
15         $field->add_subfields( "a", "1st ed." );
16

DESCRIPTION

18       Defines MARC fields for use in the MARC::Record module.  I suppose you
19       could use them on their own, but that wouldn't be very interesting.
20

EXPORT

22       None by default.  Any errors are stored in $MARC::Field::ERROR, which
23       $MARC::Record usually bubbles up to $MARC::Record::ERROR.
24

METHODS

26       new()
27
28       The constructor, which will return a MARC::Field object. Typically you
29       will pass in the tag number, indicator 1, indicator 2, and then a list
30       of any subfield/data pairs. For example:
31
32         my $field = MARC::Field->new(
33              245, '1', '0',
34              'a' => 'Raccoons and ripe corn / ',
35              'c' => 'Jim Arnosky.'
36         );
37
38       Or if you want to add a field < 010 that does not have indicators.
39
40         my $field = MARC::Field->new( '001', ' 14919759' );
41
42       tag()
43
44       Returns the three digit tag for the field.
45
46       indicator(indno)
47
48       Returns the specified indicator.  Returns "undef" and sets
49       $MARC::Field::ERROR if the indno is not 1 or 2, or if the tag doesn't
50       have indicators.
51
52       is_control_field()
53
54       Tells whether this field is one of the control tags from 001-009.
55
56       subfield(code)
57
58       When called in a scalar context returns the text from the first sub‐
59       field matching the subfield code.
60
61           my $subfield = $field->subfield( 'a' );
62
63       Or if you think there might be more than one you can get all of them by
64       calling in a list context:
65
66           my @subfields = $field->subfield( 'a' );
67
68       If no matching subfields are found, "undef" is returned in a scalar
69       context and an empty list in a list context.
70
71       If the tag is less than an 010, "undef" is returned and
72       $MARC::Field::ERROR is set.
73
74       subfields()
75
76       Returns all the subfields in the field.  What's returned is a list of
77       list refs, where the inner list is a subfield code and the subfield
78       data.
79
80       For example, this might be the subfields from a 245 field:
81
82               (
83                 [ 'a', 'Perl in a nutshell :' ],
84                 [ 'b', 'A desktop quick reference.' ],
85               )
86
87       data()
88
89       Returns the data part of the field, if the tag number is less than 10.
90
91       add_subfields(code,text[,code,text ...])
92
93       Adds subfields to the end of the subfield list.
94
95           $field->add_subfields( 'c' => '1985' );
96
97       Returns the number of subfields added, or "undef" if there was an
98       error.
99
100       delete_subfield()
101
102       delete_subfield() allows you to remove subfields from a field:
103
104           # delete any subfield a in the field
105           $field->delete_subfield(code => 'a');
106
107           # delete any subfield a or u in the field
108           $field->delete_subfield(code => ['a', 'u']);
109
110       If you want to only delete subfields at a particular position you can
111       use the pos parameter:
112
113           # delete subfield u at the first position
114           $field->delete_subfield(code => 'u', pos => 0);
115
116           # delete subfield u at first or second position
117           $field->delete_subfield(code => 'u', pos => [0,1]);
118
119       You can specify a regex to for only deleting subfields that match:
120
121          # delete any subfield u that matches zombo.com
122          $field->delete_subfield(code => 'u', match => qr/zombo.com/);
123
124       delete_subfields()
125
126       Delete all subfields with a given subfield code. This is here for back‐
127       wards compatability, you should use the more flexible delete_sub‐
128       field().
129
130       update()
131
132       Allows you to change the values of the field. You can update indicators
133       and subfields like this:
134
135         $field->update( ind2 => '4', a => 'The ballad of Abe Lincoln');
136
137       If you attempt to update a subfield which does not currently exist in
138       the field, then a new subfield will be appended to the field. If you
139       don't like this auto-vivification you must check for the existence of
140       the subfield prior to update.
141
142         if ( $field->subfield( 'a' ) ) {
143           $field->update( 'a' => 'Cryptonomicon' );
144         }
145
146       If you want to update a field that has no indicators or subfields
147       (000-009) just call update() with one argument, the string that you
148       would like to set the field to.
149
150         $field = $record->field( '003' );
151         $field->update('IMchF');
152
153       Note: when doing subfield updates be aware that "update()" will only
154       update the first occurrence. If you need to do anything more compli‐
155       cated you will probably need to create a new field and use
156       "replace_with()".
157
158       Returns the number of items modified.
159
160       replace_with()
161
162       Allows you to replace an existing field with a new one. You need to
163       pass "replace()" a MARC::Field object to replace the existing field
164       with. For example:
165
166         $field = $record->field('245');
167         my $new_field = new MARC::Field('245','0','4','The ballad of Abe Lincoln.');
168         $field->replace_with($new_field);
169
170       Doesn't return a meaningful or reliable value.
171
172       as_string( [$subfields] )
173
174       Returns a string of all subfields run together.  A space is added to
175       the result between each subfield.  The tag number and subfield charac‐
176       ter are not included.
177
178       Subfields appear in the output string in the order in which they occur
179       in the field.
180
181       If $subfields is specified, then only those subfields will be included.
182
183         my $field = MARC::Field->new(
184                       245, '1', '0',
185                               'a' => 'Abraham Lincoln',
186                               'h' => '[videorecording] :',
187                               'b' => 'preserving the union /',
188                               'c' => 'A&E Home Video.'
189                       );
190         print $field->as_string( 'abh' ); # Only those three subfields
191         # prints 'Abraham Lincoln [videorecording] : preserving the union /'.
192
193       Note that subfield h comes before subfield b in the output.
194
195       as_formatted()
196
197       Returns a pretty string for printing in a MARC dump.
198
199       as_usmarc()
200
201       Returns a string for putting into a USMARC file.  It's really only use‐
202       ful by "MARC::Record::as_usmarc()".
203
204       clone()
205
206       Makes a copy of the field.  Note that this is not just the same as say‐
207       ing
208
209           my $newfield = $field;
210
211       since that just makes a copy of the reference.  To get a new object,
212       you must
213
214           my $newfield = $field->clone;
215
216       Returns a MARC::Field record.
217
218       warnings()
219
220       Returns the warnings that were created when the record was read.  These
221       are things like "Invalid indicators converted to blanks".
222
223       The warnings are items that you might be interested in, or might not.
224       It depends on how stringently you're checking data.  If you're doing
225       some grunt data analysis, you probably don't care.
226

TODO

231       See the "TODO" section for MARC::Record.
232

LICENSE

234       This code may be distributed under the same terms as Perl itself.
235
236       Please note that these modules are not products of or supported by the
237       employers of the various contributors to the code.
238

AUTHOR

240       Andy Lester, "<andy@petdance.com>"
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244perl v5.8.8                       2005-04-27                    MARC::Field(3)