Introducing perl features in Sympa tt2 templates

(A contrib from Sylvain Amrani)

TT2 is a powerful template system which allows you to add some features in Sympa. If you read the documentation on http://www.tt2.org you will be able to do some pretty unbelievable customizations in Sympa. The following example explains how to use data coming from a LDAP directory into a family template (config.tt2).

The easy way to do it is to define your own TT2 FILTER. It's quite easy (really, it is !). Usually filters do basic things like UPPERCASE. [% “hello” FILTER upper %] will write “HELLO”. We create a new FILTER that will take the listname as argument, and returns a complete list config !

Say we want to create a new “Alf” TT2 filter (Alf, for “automatic list feature”, e.g.). The method is to create a new perl module that will be used as a FILTER in a tt2 file.

Create a new Alf.pm module in your perl @INC, and in the Template::Plugin scope (for example, on a debian server, I put it in /etc/perl/Template/Plugin/Alf.pm)

You must define an Alf::filter sub that will be called by the TT2 Process.

Alf.pm :

###############################################
package Template::Plugin::Alf;
 
use strict;
use Template::Plugin::Filter;
use base qw( Template::Plugin::Filter );
 
# you can use ldap here
use Net::LDAP;
 
sub filter {
  # you get the listname in the parameter
  my ($self, $parameter) = @_;
 
  # do everything perl can do here :
  # ldap queries, computation...
 
  # looking for 'send' value in our ldap directory :
  my $ldap = Net::LDAP->new('ldap.server.com') or die "$@";
  my $mesg = $ldap->bind(...
  $mesg = $ldap->search('filter'=>"(&(cn=$parameter)(...))", 'attrs'=>['send'], 'base'=>...
 
  my $entity = $mesg->entries[0];
  my $send_parameter = $entity->get_value('send');
 
  # compute the ldap filter and put it in $filter
  my $filter = "(&(something very complicated))";
 
  # then, return the result :
 
  my $r = "
send $send_parameter
 
include_ldap_query
host ldap.server.com
suffix dc=com
user cn=admin
filter $filter
attrs mail
scope sub
select all
 
";
  return $r
 
  # if you want to break the TT2 process for some reason,
  # simply die, and the automatic list won't be created
  die if ($some_reason);
}
1;

[% USE Alf %] 
subject [% something %]
 
# some parameters come from our filter :
[% listname FILTER $Alf %]

The list config result look like

subject computed_the_traditional_way

send public

include_ldap_query
host ldap.server.com
suffix dc=com
user cn=admin
filter (&(something very complicated))
attrs mail
scope sub
select all

That's it ! You can do everything that Perl can do in during your automatic list creation (or in any other Sympa pages) !