Editing Autocompletion (section)

=== external source ===

This takes all the ideas above, and extends them to make an API call to an external data source.  This has the advantage that you are always referring to the authoritative source, but the disadvantage that you are reliant on both the network being up and the external source being available.

It breaks down into two parts:
* the autocompleter call in the web page
* the script being called

For an example, here is one way to query the RoMEO data directly:

First, set the autocompleter in the eprints workflow:
<pre>
     <component type="Field::Multi">
      <title>Article Publication Details</title>
        <field ref="publication" input_lookup_url="{$config{perl_url}}/get_journals" />
        <field ref="publisher" />
        <field ref="issn" />
      </component>
</pre>

Next have the script:
<pre>
use strict;
use HTTP::Request;
use LWP::UserAgent;
use XML::Twig;

use Data::Dumper;
use EPrints;

my $journal_data = {};

sub urldecode{
  my ($url) = @_;
  $url =~ s/%([0-9a-f][0-9a-f])/pack("C",hex($1))/egi;
  $url =~ s/\x2B/ /; # swap '+' for ' '
  return $url;
}

# XML::Twig's routine for dealing with a journal entry
sub process_journal {
  my ( $twig, $journal ) = @_;

  # get the components
  my $title = urldecode( $journal->first_child('jtitle')->text );

  my $zetoc = urldecode( $journal->first_child('zetocpub')->text ) 
                  if $journal->first_child('zetocpub');
  my $romeo = urldecode( $journal->first_child('romeopub')->text )
                  if $journal->first_child('romeopub');
  my $issn  = urldecode( $journal->first_child('issn')->text )
                  if $journal->first_child('issn');

  my $publisher = $romeo;
  $publisher = $zetoc if (not $publisher && $zetoc);
  
  # build a lub of html based on the components
  my $html .= "<li>$title";
  $html .= "<br />published by $publisher" if $publisher;
  
  $html .= "<ul>";
  if ($title) {
      $html .= "<li id='for:value:component:_publication'>$title</li>";
  }
  if ($publisher) {
      $html .= "<li id='for:value:component:_publisher'>$publisher</li>";
  }
  if ($issn) {
    $html .= "<li id='for:value:component:_issn'>$issn</li>";
  }
  $html .= "</ul></li>\n";
  warn "\n\n$html\n\n";
  # save the html
  $journal_data->{$title} = $html;

  1; 
} ## end process_journal

# get a list of journals that match the query
sub get_journals {
  my $journal = shift;
  my @html = ();

  if ($journal) {
    return ("<ul><li>keep typing....</li></ul>") if (length($journal) < 3);

    $journal =~ s/\s+/\+/;
    my $query = "http://www.sherpa.ac.uk/romeoapi.php?qtype=starts&jtitle=$journal";

    my $request = HTTP::Request->new( GET => "$query" );

    my $ua = LWP::UserAgent->new();
    my $response = $ua->request($request);
    my $content = $response->content();

    my $twig = XML::Twig->new(
                       'keep_encoding' => 1,
                       'TwigRoots' => { 'journals' => 1 },
                       'TwigHandlers' => { 'journal' => \&process_journal, }
                      );
    $twig->parse($content);
    if (scalar keys %{$journal_data}) {
      push @html, "<ul class='journals'>\n";
      foreach my $title (sort keys %{$journal_data}) {
        push @html, "$journal_data->{$title}\n";
      } ## end of  foreach my $title (sort keys %{$journal_data})
      push @html, "</ul>\n";
    } ## end of if (scalar keys %{$journal_data}) ...
  } else {
    push @html, "<!-- No journal name supplied -->\n";
  }

  return (join "\n", @html)

} ## end get_journals

my $session = EPrints::Session->new();

# we need the send an initial content-type
print <<END;
<?xml version="1.0" encoding="UTF-8" ?>

END

# then we send the fragment of html for the autocompleter
print get_journals( lc $session->param( "q" ) );

$session->terminate;
</pre>