How to create a new Catmandu importer

Within the Catmandu framework different kinds of importers have been implemented

those for general formats like JSON, YAML or CSV
those for bibliographies formats, like MARC or AlephX
those for different Sources like arXiv, Pubmed, PloS or in general those with an OAI-Interface

Since Catmandu is designed for in a way, that can be extended… So in this little Tutorial we are going to create our own importer module Catmandu::Importer::EuroPMC.

Starting with a module

First of all, let us remember that

1. importers have to be within the namespace *Catmandu::Importer::*
2. Catmandu uses *Module::Build* as building tool

$ cpanm Module::Build Module::Starter
$ module-starter --builder="Module::Build" --module=Catmandu::Importer::EuroPMC --author="Vitali" /
-- email="vitali@example.com"

Now, change directory to Catmandu-Importer-EuroPMC and open the file lib/Catmandu/Importer/EuroPMC.pm.

Structure of an importer module

package Catmandu::Importer::EuroPMC;

use Catmandu::Sane;
use Moo;

with 'Catmandu::Importer';

use constant BASE_URL => 'http://www.ebi.ac.uk/europepmc/webservices/rest';

has base => (is => 'ro', default => sub { return BASE_URL; });
has source => (is => 'ro', default => sub { return "MED"; });
has query => (is => 'ro', required => 1);

# public method
sub generator {
	my ($self) = @_;
	my $request = $self->base . "/" . $self->source . "/" . $self->query;
	# perform get request ....

	return $hashref;
}

1;

More insights in Catmandu will be dicussed in later posts.