EPrints - custom view menu size function

README.md

Adds a custom function to EPrints' repository view configuration, so you can define a subroutine for each menu level that returns the map of {id=>count} for that level.

Particularly handy when the a conflict between the menu's fields and the generated DISTINCT BY clause include NULL values in the menu despite allow_null=>0 being specified in config.

See the discussion at http://mailman.ecs.soton.ac.uk/pipermail/eprints-tech/2017-September/006807.html

cfg__cfg.d__views.pl

$c->{browse_views} = [
    # ...

    {
        id         => "person",
        menus      => [
            {
                fields               => [ "creators_id", "editors_id" ],
                new_column_at        => [ 1,             1 ],
                mode                 => "sections",
                allow_null           => 0,
                open_first_section   => 1,
                group_range_function => "EPrints::Update::Views::cluster_ranges_30",
                grouping_function    => "EPrints::Update::Views::group_by_a_to_z",
                # returns a HASHREF of { person_id=>count(eprintid), ... }
                size_function        => sub {
                    my( $repo, $filters ) = @_;
                    my $sql = "
SELECT `d`.`person_id`, COUNT(DISTINCT `d`.`eprintid`) FROM
(
  SELECT `creators_id` AS `person_id`, `eprintid`
  FROM `eprint_creators_id`
  WHERE `creators_id` IS NOT NULL AND `creators_id` <> ''
UNION
  SELECT `editors_id` AS `person_id`, `eprintid`
  FROM `eprint_editors_id`
  WHERE `editors_id` IS NOT NULL AND `editors_id` <> ''
) AS `d`
JOIN `eprint` ON `d`.`eprintid` = `eprint`.`eprintid`
WHERE `eprint`.`eprint_status` = 'archive'
AND `eprint`.`metadata_visibility` = 'show'
AND `eprint`.`replacedby` IS NULL
AND NOT EXISTS (SELECT 1 FROM `eprint` AS `e` WHERE `e`.`succeeds` = `eprint`.`eprintid`)
GROUP BY `person_id`";
                    my $sth = $repo->get_database->prepare( $sql );
                    $repo->get_database->execute( $sth, $sql );
                    my %results;
                    while( my @row = $sth->fetchrow_array )
                    {
                        my( $p, $n ) = @row;
                        $results{ $p } = $n;
                    }
                    $sth->finish;
                    return \%results;
                },
            },
        ],
        order        => "-date/title",
        variations   => [ "type", "date;truncate=4,reverse" ],
        citation     => "view",
        max_menu_age => 7 * 24 * 60 * 60,
        max_list_age => 7 * 24 * 60 * 60,
    },

    # ...
];

perl_lib__EPrints__Update__Views.pm

# ...

sub fieldlist_sizes
{
    my( $self, $path_values, $menu_level, $filters ) = @_;

    my $repo = $self->repository;

    my $dataset = $self->dataset;
    my $menus_fields = $self->menus_fields;
    $filters = $self->get_filters( $path_values ) if !defined $filters;

    my $menu_fields = $menus_fields->[$menu_level];

    # if there are lower levels that require a value being set then we need to
    # check that, otherwise we get the wrong counts at this level
    for(my $i = @$path_values; $i < @$menus_fields; ++$i)
    {
        my $menu_fields = $menus_fields->[$i];
        my $menu = $self->{menus}->[$i];
        if( !$menu->{allow_null} )
        {
            push @$filters, 
                { meta_fields => [map { $_->name } @$menu_fields], match => "SET" };
        }
    }

    # get the id/counts for the menu level requested
    my $id_map;
    my $custom_func = $self->{menus}[$menu_level]->{size_function};
    if( $custom_func )
    {
        $id_map = $self->call($custom_func, $repo, $filters);
    }
    else
    {
        my $searchexp = $dataset->prepare_search(
            filters => $filters,
        );
        $id_map = $searchexp->perform_distinctby( $menu_fields );
    }

# ...