Difference between revisions of "Perl 101 for EPrints"
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The simplest of examples, use eprints to register a session in the repository then read an (arbitrary) eprint; accessing two bits of information about it. The attributes accessed come from [[EPrint Object]] and [[API:EPrints/DataObj]]. | The simplest of examples, use eprints to register a session in the repository then read an (arbitrary) eprint; accessing two bits of information about it. The attributes accessed come from [[EPrint Object]] and [[API:EPrints/DataObj]]. |
Revision as of 01:12, 18 September 2018
Contents
Where to start
Learning Perl: Helping you get started with Perl 5.... http://learn.perl.org/
Perl Tutorials http://perldoc.perl.org/perl.html#Tutorials
Recommended books for learning Perl
Learning Perl, 6th Edition by Randal Schwartz, brian d foy, Tom Phoenix http://www.amazon.com/Learning-Perl-Randal-L-Schwartz/dp/1449303587
Programming Perl: Unmatched power for text processing and scripting Fourth Edition Edition by Tom Christiansen, brian d foy, Larry Wall, Jon Orwant http://www.amazon.com/Programming-Perl-Unmatched-processing-scripting/dp/0596004923/
Intermediate Perl Second Edition Edition by Randal L. Schwartz, brian d foy, Tom Phoenix http://www.amazon.com/Intermediate-Perl-Randal-L-Schwartz/dp/1449393098/
Using Perl in EPrints
Retrieving data from a config file
Example of a data config file under /cfg/cfg.d/example.pl
The data structure is an array of hashes (http://perldoc.perl.org/perldsc.html#ARRAYS-OF-HASHES)
$c->{etd_ms}->{fields} = [
{ tagname => 'etd_ms:type', type=> 'constant', value => "Electronic Thesis or Dissertation" },
{ tagname => 'etd_ms:degree', type => 'compound', parts => [
{ tagname => 'etd_ms:name', type => 'simple_text', eprint_fieldname => 'thesis_degree_name' },
{ tagname => 'etd_ms:level', type => 'simple_text', eprint_fieldname => 'thesis_type' },
{ tagname => 'etd_ms:discipline', type => 'simple_text', eprint_fieldname => 'department' },
{ tagname => 'etd_ms:grantor', type => 'simple_text', eprint_fieldname => 'institution' },
] },
];
Retrieving values from this config file in an "Example" export plugin under /plugins/EPrints/Plugin/Export/example.pm
package EPrints::Plugin::Export::Example;
use EPrints::Plugin::Export;
@ISA = ( "EPrints::Plugin::Export" );
[...]
my $fields = $session->get_conf('etd_ms','fields');
foreach my $field_conf (@{$fields})
{
my $tags = $plugin->generate_tag($eprint, $field_conf);
foreach my $tag (@{$tags})
{
push @dcdata, ($tag) if $tag;
}
}
Supporting function that returns an arrayref
sub generate_tag {
my ($plugin, $eprint, $field_conf) = @_;
#Constant value
if ($field_conf->{type} eq 'constant')
{
return $plugin->generate_constant_tag($eprint, $field_conf);
}
}
Supporting function that generates a tag
sub generate_constant_tag{
my ($plugin, $eprint, $field_conf) = @_;
my $tag = $plugin->_simple_tag($field_conf, $field_conf->{value});
return [ $tag ];
}
Function parameters
In perl, the following:
$obj->function($arg1, $arg2)
is equivalent to:
Class::function($obj, $arg1,$arg2)
In the example above, when we call:
my $tags = $plugin->generate_tag($eprint, $field_conf);
It is equivalent to:
my $tags = Example::generate_tag($plugin, $eprint, $field_conf);
This explains the three parameters listed in the top of the generate_tag function definition:
sub generate_tag {
my ($plugin, $eprint, $field_conf) = @_;
A basic EPrint extracting script
The simplest of examples, use eprints to register a session in the repository then read an (arbitrary) eprint; accessing two bits of information about it. The attributes accessed come from EPrint Object and API:EPrints/DataObj.
#!/usr/bin/perl -w
use EPrints;
use strict;
# Create new session for interacting with eprints
my $ep = EPrints->new( cleanup=>0 );
my $session = $ep->repository( 'REPOID');
my $id = 23743;
# Create new object referency thing for our desired eprint (23743)
$::pulled_eprint = EPrints::DataObj::EPrint->new( $session, $id );
print $::pulled_eprint->get_dataset_id . "\n";
print $::pulled_eprint->get_type . "\n";
$session->terminate();
This example can be expanded to test work in progress functions as required.