acts_as_graph¶ ↑

OMGSUPERIMPORTANT! My last update to AAG was around 2006. That’s roughly 40 years ago (in Rails-time). Consider this abandonware, posted to github in the hopes that some poor coder with way too much free time will give it a home.¶ ↑

The acts_as_graph plugin extends ActiveRecord to implement a connected graph.

acts_as_graph produces a graph structure by providing self-referencing inbound and outbound association collections to your model. It requires that you have an edge table (used in the HABTM relationship), which by default is called CLASS_edges (where CLASS is the name of your model), and which has two columns: child_id and parent_id by default.

Currently, only DAGs (Directed, Acyclic graphs) are supported.

See here and here for more information.

class Task < ActiveRecord::Base
  acts_as_graph :edge_table => "dependencies"
end

# task1
#  +- task2
#  |   +- task3
#  |   \- task4
#  \- task3

task1 = Task.new(:name => "Task 1")
task2 = Task.new(:name => "Task 2")
task3 = Task.new(:name => "Task 3")
task4 = Task.new(:name => "Task 4")

task1.children << [task2, task3]
task2.children << task3
task2.children << task

task1.parents                                           => []
task3.parents                                           => [task1, task2]
task1.children                                          => [task2, task3]
task1.children.recursive.to_a                           => [task2, task3, task4]
task1.children.recursive.each { |child| child.spank }   => nil

See more examples under test/models.

The recursive object (of the Recursive class) is added to the parents and children associations, and represents a DFS on those collections. When coerced into an array, it gathers all of the child or parent records recursively (obviously) into a single array.

When each is called on the recursive object, it yields against each record in turn.

This means that some operations (such as include?) will be faster when run with the each implementation.

The following options are supported, but some have yet to be implemented:

edge_table

HABTM table that represents graph edges. Defaults to class_name_id.

parent_col

Column in edge_table that references the parent node. Defaults to parent_id.

child_col

Column in edge_table that references the child node. Defaults to child_id.

child_collection

Name of the child collection. Defaults to children.

parent_collection

Name of the child collection. Defaults to parents.

allow_cycles

Determines whether or not the graph is cyclic. Defaults to false. Cyclic graphs are not yet implemented.

directed

Determines whether or not the graph is directed. Defaults to true. Undirected graphs are not yet implemented.

Future directions¶ ↑

The following features are being worked on for this plugin:

• Cyclic and undirected graphs.

• DFS/BFS choices for the recursive object.

• Converting the recursive object to a proxy (such as the how the other association proxies are done).

Download¶ ↑

You can get acts_as_graph via cvs. From the rails project directory, run:

./script/plugin install -x svn://rubyforge.com/var/svn/acts_as_graph