=head1 NAME
-DBIx::Class::Tree::AdjacencyList - Manage a tree of data using the common adjacency list model. (EXPERIMENTAL)
+DBIx::Class::Tree::AdjacencyList - Manage a tree of data using the common adjacency list model.
=head1 SYNOPSIS
name TEXT NOT NULL
);
-In your Schema or DB class add Tree::AdjacencyList to the top
+In your Schema or DB class add Tree::AdjacencyList to the top
of the component list.
__PACKAGE__->load_components(qw( Tree::AdjacencyList ... ));
package My::Employee;
__PACKAGE__->parent_column('parent_id');
+Optionally, automatically maintane a consistent tree structure.
+
+ __PACKAGE__->repair_tree( 1 );
+
Thats it, now you can modify and analyze the tree.
#!/usr/bin/perl
use My::Employee;
-
+
my $employee = My::Employee->create({ name=>'Matt S. Trout' });
-
+
my $rs = $employee->children();
my @siblings = $employee->children();
-
+
my $parent = $employee->parent();
$employee->parent( 7 );
=head1 DESCRIPTION
-This module provides methods for working with adjacency lists. The
-adjacency list model is a very common way of representing a tree structure.
-In this model each row in a table has a prent ID column that references the
-primary key of another row in the same table. Because of this the primary
-key must only be one column and is usually some sort of integer. The row
-with a parent ID of 0 is the root node and is usually the parent of all
-other rows. Although, there is no limitation in this module that would
+This module provides methods for working with adjacency lists. The
+adjacency list model is a very common way of representing a tree structure.
+In this model each row in a table has a prent ID column that references the
+primary key of another row in the same table. Because of this the primary
+key must only be one column and is usually some sort of integer. The row
+with a parent ID of 0 is the root node and is usually the parent of all
+other rows. Although, there is no limitation in this module that would
stop you from having multiple root nodes.
-
-
=head1 METHODS
-
-
=head2 parent_column
__PACKAGE__->parent_column('parent_id');
-Declares the name of the column that contains the self-referential
-ID which defines the parent row. Defaults to "parent_id". This
-will create a has_many (children) and belongs_to (parent)
-relationship.
+Declares the name of the column that contains the self-referential
+ID which defines the parent row. 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
+This method also sets up an additional has_many relationship called
+parents which is useful when you want to treat an adjacency list
as a DAG.
=cut
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" }, {cascade_delete=>0} );
+ $class->has_many( 'parents' => $class => { "foreign.$primary_col" => "self.$parent_col" }, { cascade_delete => 0, cascade_copy => 0 } );
$class->_parent_column( $parent_col );
return 1;
}
return $class->_parent_column();
}
+=head2 repair_tree
+
+ __PACKAGE__->repair_tree( 1 );
+
+When set a true value this flag causes all changes to a node's parent to
+trigger an integrity check on the tree. If, when changing a node's parent
+to one of it's descendents then all its children will first be moved to have
+the same current parent, and then the node's parent is changed.
+
+So, for example, if the tree is like this:
+
+ A
+ B
+ C
+ D
+ E
+ F
+
+And you execute:
+ $b->parent( $d );
+
+Since D is a descendant of B then all of D's siblings get their parent
+changed to A. Then B's parent is set to D.
+
+ A
+ C
+ D
+ B
+ E
+ F
+
+=cut
+
+__PACKAGE__->mk_classdata( 'repair_tree' => 0 );
=head2 parent
$employee->parent( $parent_obj );
$employee->parent( $parent_id );
-Retrieves the object's parent object, or changes the object's
-parent to the specified parent or parent ID. If you would like
+Retrieves the object's parent object, or changes the object's
+parent to the specified parent or parent ID. If you would like
to make the object the root node, just set the parent to 0.
-If you are setting the parent then 0 will be returned if the
-specified parent is already the object's parent and 1 on
+If you are setting the parent then 0 will be returned if the
+specified parent is already the object's parent and 1 on
success.
=cut
$new_parent = $new_parent->id() || croak('Parent object does not have an ID');;
}
return 0 if ($new_parent == ($self->get_column($parent_col)||0));
+
+ if ($self->repair_tree()) {
+ my $found = $self->has_descendant( $new_parent );
+ if ($found) {
+ my $children = $self->children();
+
+ while (my $child = $children->next()) {
+ $child->parent( $self->$parent_col() );
+ }
+ }
+ }
+
$self->set_column( $parent_col => $new_parent );
$self->update();
return 1;
}
return $self->_parent();
}
+=head2 ancestors
+
+ @list = $employee->ancestors();
+
+Returns a list of ancestors starting with a record's
+parent and moving toward the tree root.
+=cut
+
+sub ancestors {
+ my $self = shift;
+ my @ancestors = ();
+ my $rec = $self;
+ while ($rec = $rec->parent) {
+ push(@ancestors, $rec);
+ }
+ return @ancestors;
+}
-=head2 set_parent
+=head2 has_descendant
- $employee->set_parent($boss_obj);
- $employee->set_parent($boss_id);
+ if ($employee->has_descendant( $id )) { ... }
-A syntactic alternative to ->parent() for setting only.
+Returns true if the object has a descendant with the
+specified ID.
=cut
-sub set_parent {
- my $self = shift;
- if (@_) {
- my $new_parent = shift;
- my $parent_col = $self->_parent_column();
- if (ref($new_parent)) {
- $new_parent = $new_parent->id() || croak('Parent object does not have an ID');;
+sub has_descendant {
+ my ($self, $find_id) = @_;
+
+ my $children = $self->children();
+ while (my $child = $children->next()) {
+ if ($child->id() eq $find_id) {
+ return 1;
}
- return 0 if ($new_parent == ($self->get_column($parent_col)||0));
- $self->set_column( $parent_col => $new_parent );
- $self->update();
- return 1;
+ return 1 if ($child->has_descendant( $find_id ));
}
-}
-
+ return 0;
+}
=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
+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();
my @children = $employee->children();
-Returns a list or record set, depending on context, of all
-the objects one level below the current one. This method
-is created when parent_column() is called, which sets up a
+Returns a list or record set, depending on context, of all
+the objects one level below the current one. This method
+is created when parent_column() is called, which sets up a
has_many relationship called children.
-=head2 add_child
+=head2 attach_child
- $parent->add_child( $child );
- $parent->add_child( $child, $child, ... );
+ $parent->attach_child( $child );
+ $parent->attach_child( $child, $child, ... );
-Sets the child, or children, to the new parent. Returns 1
-on success and returns 0 if the parent object already has
+Sets the child, or children, to the new parent. Returns 1
+on success and returns 0 if the parent object already has
the child.
=cut
-sub add_child {
+sub attach_child {
my $self = shift;
my $return = 1;
foreach my $child (@_) {
return $return;
}
-
-
-=head2 add_children
-
-An alias for add_child.
-
-=cut
-
-sub add_children {
- my $self = shift;
- return $self->add_child(@_);
-}
-
-
-
=head2 siblings
my $rs = $node->siblings();
my @siblings = $node->siblings();
-Returns either a result set or an array of all other objects
+Returns either a result set or an array of all other objects
with the same parent as the calling object.
=cut
return $rs;
}
+=head2 attach_sibling
+ $obj->attach_sibling( $sibling );
+ $obj->attach_sibling( $sibling, $sibling, ... );
-=head2 add_sibling
-
- $obj->add_sibling( $sibling );
- $obj->add_sibling( $sibling, $sibling, ... );
-
-Sets the passed in object(s) to have the same parent
-as the calling object. Returns 1 on success and
+Sets the passed in object(s) to have the same parent
+as the calling object. Returns 1 on success and
0 if the sibling already has the same parent.
=cut
-sub add_sibling {
+sub attach_sibling {
my $self = shift;
my $return = 1;
foreach my $node (@_) {
return $return;
}
-
-
=head2 is_leaf
if ($obj->is_leaf()) { ... }
sub is_leaf {
my( $self ) = @_;
- return $self->result_source->resultset->search(
+
+ my $has_child = $self->result_source->resultset->search(
{ $self->_parent_column => $self->id() },
{ limit => 1 }
)->count();
-}
-
+ return $has_child ? 0 : 1;
+}
=head2 is_root
sub is_root {
my( $self ) = @_;
- return ( $self->get_column( $self->_parent_column ) ? 1 : 0 );
+ return ( $self->get_column( $self->_parent_column ) ? 0 : 1 );
}
-
-
=head2 is_branch
if ($obj->is_branch()) { ... }
-Returns 1 if the object has a parent and has children.
+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());
-}
-
-
-
-=head2 descendents
-
-Returns a flat list of *all* the node's descendents.
-Dangerously recursive. Use with extreme caution. May contain
-nuts.
-
-=cut
-
-sub descendents {
- my $self = shift;
- my @descendents;
- for my $child ($self->children) {
- push @descendents, $child, $child->descendents;
- }
- return @descendents;
-}
-
-
-
-=head2 pharaoh_delete
-
-Deletes a node and all it's children (even if cascade_delete is off)
-
-=cut
-
-sub pharaoh_delete {
- my $self = shift;
- for my $child ($self->children) {
- $child->pharaoh_delete;
- }
- $self->delete;
+ return ( ($self->is_leaf() or $self->is_root()) ? 0 : 1 );
}
-
-
-=head2 grandmother_delete
-
-Deletes a node and sends all its children to live with their grandmother
-
-=cut
-
-sub grandmother_delete {
- my $self = shift;
- $self->parent->add_children($self->children);
- $self->delete;
-}
-
-
-
-=head2 promote_eldest_child_delete
-
-Deletes a node and promotes the first of it children to take its place.
-If that node already had children, they will now be siblings of the new
-parent node's former siblings (which are now its children).
-
-=cut
-
-sub promote_eldest_child_delete {
- my $self = shift;
- my @children = $self->children;
- my $eldest = shift @children;
- $eldest->set_parent($self->parent);
- $eldest->add_children(@children);
- $self->delete;
-}
-
-
-
-=head2
-
-Replaces the current node with the given replacement, and then deletes the
-current node. The replacement node with have the old node's parent, and its
-children will be the union of its original children and the old node's
-children.
-
-=cut
-
-sub replace_with_and_delete {
- my ($self, $replacement) = @_;
- $replacement->add_children($self->children);
- $replacement->set_parent($self->parent);
- $self->delete;
-}
-
-
-
=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
+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
projects / dbsrgits/DBIx-Class-Tree.git / blobdiff