Editing Create Export Plugins (section)

===Conversion===

The 'output_dataobj' function takes a dataobj (in our case an eprint object) and returns a perl scalar which will be the output.  We are going to extract some data from the dataobj using EPrints API calls.

Note that by convention, '$plugin' is used instead of '$self'.
<pre>
 sub output_dataobj
 {
       my( $plugin, $dataobj ) = @_;
 
       my $r = "";
       if ($dataobj->exists_and_set("userid"))                                       #userid may not be set if the deposit was done by a script.
       {
               my $session = $plugin->{"session"}; 
               my $userid = $dataobj->get_value( "userid" );
               my $depositor_obj = new EPrints::DataObj::User($session, $userid);    #create a user object
               my $depositor = $depositor_obj->get_value( "username" );              #get the user ID
               if ($depositor =~ m/[\n" ,]/)                                         #Check for illegal CSV characters
               {
                       $depositor =~ s/"/""/g;                                       #escape quotes
                       $depositor = '"' . $depositor . '"';                          #delimit text
               }
               $r .= $depositor;
       }
       else
       {
               $r .= '"Depositor Unknown"';
       }
       $r .= ',"' . $dataobj->get_value( "datestamp" ) . '"' ."\n";                   #datestamp is always set, and contains a space so needs delimiting
 
       return $r;
 }
</pre>
Notes:

* Retreiving the username takes a little fancy footwork because the EPrints object contains depositor userids.  We need to create a user object and get the username from that.
* We use '$dataobj->get_value' to retrieve metadata from the eprint (or user) objects.
* As we're outputting in CSV, we need to do a little normalisation.