Editing Upgrading EPM Packages (section)

=Example= 

The starting point for this is our Screen plug-in where the POSTINST and PRERM methods are defined (see [[XML manipulation of the EPrints Workflow using a Bazaar Package]]).

To enable upgrades we simply add an upgrade sub alongside these methods:

  sub allow_action_upgrade
  {
        my ( $self ) = @_;
  
        return 1;
  }
  
  # The upgrade method, this will call all upgrade subs individually between the old version number and the new version number.
  sub action_upgrade
  {
        my ( $self, $old_version_number, $new_version_number ) = @_;
    
        my @versions = qw(
                        0.0.1
                        0.0.2
        );
        
        for(my $i = 0; $i < $#versions; ++$i)
        {
               if( $old_version_number eq $versions[$i] )
               {
                        no strict 'refs';
                        my $f = "upgrade_".$versions[$i]."_to_".$versions[$i+1];
                        $f =~ s/\./_/g;
                        &$f( $self );
                        $old_version_number = $versions[$i+1];
               }
        }
  }
   
  sub upgrade_0_0_1_to_0_0_2
  {
        my ( $self ) = @_;
  
        print STDERR "IN THE UPGRADE ROUTINE FOR 0.0.1 to 0.0.2 \n\n";
  
        # Add your API calls POSTINST like stuff here to upgrade versions. 
  }


So all you need to do is define potentially lots of upgrade_X_X_X_to_X_X_Z routines to handle all the upgrades and add this version number (which needs an upgrade routine).

If people are upgrading from 0.0.1 to 0.0.5 then potentially 4 of these upgrade methods will be called.

[[Category:EPrints_Bazaar]]