is_* methods and primary key validation

[dbsrgits/DBIx-Class-Tree.git] / lib / DBIx / Class / Tree / AdjacencyList.pm

diff --git a/lib/DBIx/Class/Tree/AdjacencyList.pm b/lib/DBIx/Class/Tree/AdjacencyList.pm
index b3df744..58c0961 100644 (file)
--- a/lib/DBIx/Class/Tree/AdjacencyList.pm
+++ b/lib/DBIx/Class/Tree/AdjacencyList.pm
@@ -1,7 +1,9 @@
-# vim: ts=8:sw=4:sts=4:et
 package DBIx::Class::Tree::AdjacencyList;
+# vim: ts=8:sw=4:sts=4:et
+
 use strict;
 use warnings;
+
 use base qw( DBIx::Class );
 use Carp qw( croak );
 
@@ -64,6 +66,10 @@ ID which defines the parent row.  Defaults to "parent_id".  This
 will create a has_many (children) and belongs_to (parent) 
 relationship.
 
+This method also setups an additional has_many relationship called 
+parents which is useful when you want to treat an adjacency list 
+as a DAG.
+
 =cut
 
 __PACKAGE__->mk_classdata( '_parent_column' => 'parent_id' );
@@ -75,6 +81,7 @@ sub parent_column {
         my $primary_col = ($class->primary_columns())[0];
         $class->belongs_to( '_parent' => $class => { "foreign.$primary_col" => "self.$parent_col" } );
         $class->has_many( 'children' => $class => { "foreign.$parent_col" => "self.$primary_col" } );
+        $class->has_many( 'parents' => $class => { "foreign.$primary_col" => "self.$parent_col" } );
         $class->_parent_column( $parent_col );
         return 1;
     }
@@ -113,6 +120,17 @@ sub parent {
     return $self->_parent();
 }
 
+=head2 parents
+
+  my $parents = $node->parents();
+  my @parents = $node->parents();
+
+This has_many relationship is not that useful as it will 
+never return more than one parent due to the one-to-many 
+structure of adjacency lists.  The reason this relationship 
+is defined is so that this tree type may be treated as if 
+it was a DAG.
+
 =head2 children
 
   my $children_rs = $employee->children();
@@ -189,9 +207,114 @@ sub attach_sibling {
     return $return;
 }
 
+=head2 is_leaf
+
+  if ($obj->is_leaf()) { ... }
+
+Returns 1 if the object has no children, and 0 otherwise.
+
+=cut
+
+sub is_leaf {
+    my( $self ) = @_;
+    return $self->result_source->resultset->search(
+        { $self->_parent_column => $self->id() },
+        { limit => 1 }
+    )->count();
+}
+
+=head2 is_root
+
+  if ($obj->is_root()) { ... }
+
+Returns 1 if the object has no parent, and 0 otherwise.
+
+=cut
+
+sub is_root {
+    my( $self ) = @_;
+    return ( $self->get_column( $self->_parent_column ) ? 1 : 0 );
+}
+
+=head2 is_branch
+
+  if ($obj->is_branch()) { ... }
+
+Returns 1 if the object has a parent and has children.  
+Returns 0 otherwise.
+
+=cut
+
+sub is_branch {
+    my( $self ) = @_;
+    return ( ($self->is_leaf() or $self->is_root()) ? 0 : 1 );
+}
+
+=head2 set_primary_key
+
+This method is an override of DBIx::Class' method for setting the 
+class' primary key column(s).  This method passes control right on 
+to the normal method after first validating that only one column is 
+being selected as a primary key.  If more than one column is then 
+an error will be thrown.
+
+=cut
+
+sub set_primary_ley {
+    my $self = shift;
+    if (@_>1) {
+        croak('You may only specify a single column as the primary key for adjacency tree classes');
+    }
+    return $self->next::method( @_ );
+}
+
 1;
 __END__
 
+=head1 INHERITED METHODS
+
+=head2 DBIx::Class
+
+=over 4
+
+=item *
+
+L<mk_classdata|DBIx::Class/mk_classdata>
+
+=item *
+
+L<component_base_class|DBIx::Class/component_base_class>
+
+=back
+
+=head2 DBIx::Class::Componentised
+
+=over 4
+
+=item *
+
+L<inject_base|DBIx::Class::Componentised/inject_base>
+
+=item *
+
+L<load_components|DBIx::Class::Componentised/load_components>
+
+=item *
+
+L<load_own_components|DBIx::Class::Componentised/load_own_components>
+
+=back
+
+=head2 Class::Data::Accessor
+
+=over 4
+
+=item *
+
+L<mk_classaccessor|Class::Data::Accessor/mk_classaccessor>
+
+=back
+
 =head1 AUTHOR
 
 Aran Clary Deltac <bluefeet@cpan.org>