Create Export Plugins

Export plugins for anything but eprints are beyond the scope of this howto.

Imagine we want to create an export plugin that will take a group of eprints (or a single eprint) and output a csv file containing a list of who deposited the eprints, and the dates on which they were deposited.

Essentials

The top of the plugin should look like this:

package EPrints::Plugin::Export::DepositorActivity;

use Unicode::String qw( utf8 );
use EPrints::Plugin::Export;
use EPrints::DataObj::User;
@ISA = ( "EPrints::Plugin::Export" );
use strict;

sub new
{
       my( $class, %params ) = @_;

       my $self = $class->SUPER::new( %params );

       $self->{name} = "Depositor Activity";
       $self->{accept} = [ 'list/eprint', 'dataobj/eprint' ];
       $self->{visible} = "all";
       $self->{suffix} = ".csv";
       $self->{mimetype} = "text/csv";

       return $self;
}

This will create a filter object, and set a number of configuration constants:

• name - The name of the filter
• accept - A list detailing what the filter will take as inputs. In this case, a list of eprints or a single eprint. It is possible to write filters for dataobj types 'eprint', 'user', 'subject', 'history', 'access' and '*' (all).
• visible - Who can see this filter. It's set to 'all' above so that anyone can use it. It could be set to 'staff' to only allow repository staff to use it. If set to 'API' then the filter is not available through the web interface.
• suffix - Appended to the url to create a filename extension.
• mimetype - Should be set to the correct mime type for the output of the filter.

Note that 'name' and 'accept' are essential. These allow the filter to register itself with EPrints.

We will be extracting the username of the depositor, so we need to use 'EPrints::DataObj::User'.

Converting the dataobj

The 'output_dataobj' function takes a dataobj (in our case an eprint object) and returns a perl scalar which will be the output. We are going to extract some data from the dataobj using EPrints API calls.

Note that by convention, '$plugin' is used instead of '$self'.

sub output_dataobj
{
      my( $plugin, $dataobj ) = @_;

      my $r = "";
      if ($dataobj->exists_and_set("userid"))
      {
              my $session = $plugin->{"session"};
              my $userid = $dataobj->get_value( "userid" );

              my $depositor_obj = new EPrints::DataObj::User($session, $userid);
               my $depositor = $depositor_obj->get_value( "username" );
              if ($depositor =~ m/[\n" ,]/)  #Check for illegal CSV characters
              {
                      $depositor =~ s/"/""/g; #escape quotes
                      $depositor = '"' . $depositor . '"'; #delimit text
              }
              $r .= $depositor;
      }
      else
      {
              $r .= '"Depositor Unknown"';
      }
      $r .= ',' . $dataobj->get_value( "datestamp" ) . "\n";

      return $r;
}

Put it in a Module

Put all this into a file called 'DepositorActivity.pm' and save the file into the 'eprints3/perl_lib/EPrints/Plugin/Export/' directory. Don't forget to add this to the bottom of the file:

1;