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package Koha::REST::Plugin::Pagination;
# This file is part of Koha.
#
# Koha is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# Koha is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Koha; if not, see <http://www.gnu.org/licenses>.
use Modern::Perl;
use Mojo::Base 'Mojolicious::Plugin';
=head1 NAME
Koha::REST::Plugin::Pagination
=head1 API
=head2 Mojolicious::Plugin methods
=head3 register
=cut
sub register {
my ( $self, $app ) = @_;
=head2 Helper methods
=head3 add_pagination_headers
my $patrons = Koha::Patrons->search( ... );
$c->add_pagination_headers({
total => $patrons->count,
params => {
_page => ...
_per_page => ...
...
}
});
Adds a Link header to the response message $c carries, following RFC5988, including
the following relation types: 'prev', 'next', 'first' and 'last'.
It also adds X-Total-Count containing the total results count, and X-Base-Total-Count containing the total of the non-filtered results count.
If page size is omitted, it defaults to the value of the RESTdefaultPageSize syspref.
=cut
$app->helper(
'add_pagination_headers' => sub {
my ( $c, $args ) = @_;
my $total = $args->{total};
my $base_total = $args->{base_total};
my $req_page = $args->{params}->{_page} // 1;
my $per_page = $args->{params}->{_per_page} //
C4::Context->preference('RESTdefaultPageSize') // 20;
my $pages;
if ( $per_page == -1 ) {
$req_page = 1;
$pages = 1;
}
else {
$pages = int $total / $per_page;
$pages++
if $total % $per_page > 0;
}
my @links;
if ( $per_page != -1 and $pages > 1 and $req_page > 1 ) { # Previous exists?
push @links,
_build_link(
$c,
{ page => $req_page - 1,
per_page => $per_page,
rel => 'prev',
params => $args->{params}
}
);
}
if ( $per_page != -1 and $pages > 1 and $req_page < $pages ) { # Next exists?
push @links,
_build_link(
$c,
{ page => $req_page + 1,
per_page => $per_page,
rel => 'next',
params => $args->{params}
}
);
}
push @links,
_build_link( $c,
{ page => 1, per_page => $per_page, rel => 'first', params => $args->{params} } );
push @links,
_build_link( $c,
{ page => $pages, per_page => $per_page, rel => 'last', params => $args->{params} } );
# Add Link header
$c->res->headers->add( 'Link' => join( ',', @links ) );
# Add X-Total-Count header
$c->res->headers->add( 'X-Total-Count' => $total );
$c->res->headers->add( 'X-Base-Total-Count' => $base_total );
return $c;
}
);
=head3 dbic_merge_pagination
$filter = $c->dbic_merge_pagination({
filter => $filter,
params => {
page => $params->{_page},
per_page => $params->{_per_page}
}
});
Adds I<page> and I<rows> elements to the filter parameter.
=cut
$app->helper(
'dbic_merge_pagination' => sub {
my ( $c, $args ) = @_;
my $filter = $args->{filter};
$filter->{page} = $args->{params}->{_page};
$filter->{rows} = $args->{params}->{_per_page};
return $filter;
}
);
}
=head2 Internal methods
=head3 _build_link
my $link = _build_link( $c, { page => 1, per_page => 5, rel => 'prev' });
Returns a string, suitable for using in Link headers following RFC5988.
=cut
sub _build_link {
my ( $c, $args ) = @_;
my $params = $args->{params};
$params->{_page} = $args->{page};
$params->{_per_page} = $args->{per_page};
my $link = '<'
. $c->req->url->clone->query(
$params
)->to_abs
. '>; rel="'
. $args->{rel} . '"';
# TODO: Find a better solution for this horrible (but needed) fix
$link =~ s|api/v1/app\.pl/||;
return $link;
}
1;