Add a parallel authentication routine

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Revision as of 14:58, 20 September 2007 by Kiz (talk | contribs) (Changing the way the field is ''rendered'')
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This is a real-world example.


Use an external agency that may define a persistent User ID (a "puid") for someone visiting the repository.


An eprints user may have an identifying puid associated with their account. If a user arrives with a piud that matches one held in the tables, that user profile is loaded. If not, use the standard eprints login system is used to identify the user.

There are situations where a user may come in with a different puid (visiting a different institution, moving to a different institution, a change at institutional level, etc), and a user should be able to change the puid associated with their account.

Note: puids are opaque, so humans do not recognise the opaque string as meaning anything, and asking a user to type in a puid is prone to typo-errors. However, puids are assigned by an institution, so I made sure I got the name of the institution that authenticated the user along with the puid.

How To Do It

The very basics

Step 1 is to set up the basic requirement: We need fields in the user object (archives/ARCHIVEID/cfg/cfg.d/

        'name' => 'puid',
        'type' => 'text',

and the corresponding entries in the workflow and phrases files:

Workflows (archives/ARCHIVEID/cfg/workflows/user/default.xml)

    <component type="Field::Multi">
      <title><epc:phrase ref="user_section_account" /></title>
      <epc:if test="usertype != 'minuser'"><field ref="email"/></epc:if>
      <field ref="hideemail"/>
      <field ref="password"/>
      <field ref="puid" /> <!-- NEW ITEM -->

phrases (archives/ARCHIVEID/cfg/lang/en/phrases/user_fields.xml):

    <epp:phrase id="user_fieldname_puid">Devolved Authentication</epp:phrase>
    <epp:phrase id="user_fieldhelp_puid">This option determines which (if any)
                   institution is recognised as providing the correct devolved
                   authentication for this depositor.</epp:phrase>

NOTE If you alter the file, you need to rebuild the database, which means wiping and restarting (or doing clever stuff with SQL), so make sure you do all this before you start putting data into the repository

Field rendering Problem

However, this means that we get a text input item, not what we want (see the comment above about users typing in opaque strings)

Changing the way the field is rendered

In Step 2 we alter the way the object deals with the 'puid' field. the user field is changed and we define alternative methods for rendering the field (as a fragment of xhtml) and for changing the value:

        'name'                => 'puid',
        'type'                => 'text',
        'render_single_value' => \&render_puid,
        'render_input'        => \&select_puid,

In archives/ARCHIVEID/cfg/cfg.d/ we also add the two methods:

sub render_puid
    my ( $session, $field, $value ) = @_;

		return $session->make_text("You have no automatic authentication");

	# split the value into two parts, on the first # (there may be more than one..)
	my ( $rawpuid, $inst) = split /#/, $value, 2; 
	if( !EPrints::Utils::is_set($inst) )
        	return $session->make_text(
            		"You have an institution defined, but it is un-named");

        $inst =~ s/\+/ /g;
        # we should have an institutionl name set, but just in case...
        return $session->make_text(
            "Your defined authenticating institution is $inst")


sub select_puid {
    my ( $field, $session, $puid, $dataset, $staff, $hidden_fields, $user,
        $basename ) = @_;
   my @order = ('none');
   my $desc = { none => 'No PUID stuff' };
   my $values = { 'none' => '' };

   my $default = 'none';

   if( EPrints::Utils::is_set( $value ) )
     push @order, 'old';
     $values->{old} = $value;
     my ($uid, $org) = split /\#/, $value;
     $org =~ s/\+/ /g;
     $desc->{old} = "Current value: $org";
     $default = 'old';

   my $cookie_puid = $session->puid_from_cookie;
   if( defined $cookie_puid && $cookie_puid ne $value )
     push @order, 'new';
     $values->{new} = $cookie_puid;
     my ($uid, $org) = split /\#/, $cookie_puid;
     $org =~ s/\+/ /g;
     $desc->{new} = "New value: $org";

   my $div = $session->make_element( "div" );
   foreach my $bit ( @order ) 
      my $div2 = $session->make_element( "div" );
      my $label = $session->make_element( "label" );
      $div->appendChild( $div2 );
      $div2->appendChild( $label );
      my %iopts = (
                value=>$values->{$bit} );
      if( $default eq $bit ) { $iopts{checked} = 'checked'; }
      $label->appendChild( $session->make_element( "input", %iopts ) );
      $label->appendChild( $session->make_text( " ".$desc->{$bit} ) );
   return $div;


Problem: needs data set at the beginning of each session

This works well, however there is a small snag - how are we setting $c->notes->get('this_puid');?


Well, this is all done in perl_lib/EPrints/, specifically in _current_user_auth_cookie:

sub _current_user_auth_cookie
	my( $self ) = @_;

	if( !defined $self->{request} )
		# not a cgi script.
		return undef;

  # Hack to ensure that the Repository Junction details are set before
  # the local EP3 cookie stuff takes over
  my %cookie;
  my ($puid, $orgname);
	# we won't have the cookie for the page after login.
	my $c = $self->{request}->connection;

  unless ( $c->notes->get( "this_puid" ) ) {
    warn "Not got RJunction cookie";
    my $rj_cookie = EPrints::Apache::AnApache::cookie(  $self->get_request, "depot_authen" );

    if( defined $rj_cookie ) {
      %cookie = split /&/, $rj_cookie;
      ## Do clever stuff to extract $puid and $orgname from the cookie ##
      $c->notes->set( "this_puid", $puid );
      $c->notes->set( $puid, $orgname );
    } ## end of cookie defined
  } ## end of "if note set"
  ## end of first bit of hack, back to normal, but the coding is slightly altered

  my $userid = $c->notes->get( "userid" );
  $c->notes->set( "userid", 'undef' );

  my $user;
  # Check for a userid set in the session notes area
  if( EPrints::Utils::is_set( $userid ) && $userid ne 'undef' )
    $user = EPrints::DataObj::User->new( $self, $userid );
  # if not, check for an EPrints user session cookie
  unless ( $user ) {
    my $cookie = EPrints::Apache::AnApache::cookie( $self->get_request, "eprints_session" );
    if ( $cookie  ) {
      my $remote_addr = $c->get_remote_host;
      $userid = $self->{database}->get_ticket_userid( $cookie, $remote_addr );
      $user = EPrints::DataObj::User->new( $self, $userid ) if EPrints::Utils::is_set( $userid );

  # If still not, can we authenticate with a puid?
  unless ( $user ) {
    if ( $c->notes->get( "this_puid" ) ) {
      $user = EPrints::DataObj::User::user_with_puid( $self, $c->notes->get( "this_puid" ) );
  # if we get a user, by hook or by crook, set some details in the notes section
  if ( $user ) {
    if ( $user->get_value('puid') ) {
      $c->notes->set( 'puid' , $user->get_value('puid' ) );
      $c->notes->set( $user->get_value('puid') ,
                      $user->get_value('puid_inst') );
    return $user;
  # if we really cannot find a user, return undef (no user found)
  return undef;

So how do I save two fields at once?

There is one small problem, although we can change the puid held in the user object, we're not updating the nice piece of text held in puid_inst

Altering the way the submitted data is handled

Step 3 is to save the name of the authenticting institute as well as the puid, so that we can display the appropriate name.

We need another subroutine in archives/ARCHIVEID/cfg/cfg.d/

        'name'                => 'puid',
        'type'                => 'text',
        'render_single_value' => \&render_puid,
        'render_input'        => \&select_puid,
       ''' 'fromform'            => \&fromform_puid,'''

and the corresponding method:

sub fromform_puid {
    my ( $value, $session ) = @_;
    # get the user object from the session
    my $c = $session->{request}->connection;
    my $inst = $c->notes->get($value);
    my $user = $session->current_user;

    # save the text associated with the puid in the sesion notes
    $user->set_value('puid_inst', $inst );

    # return the value, unchanged
    return $value;    

There is a problem

It's not working :sad: