MIGRATION.md

Migrating from dagnabit 2 to dagnabit 3

1. Polymorphic associations are no longer supported. If you need a polymorphic graph, convert your data model to use single-table inheritance.

2. The *_transitive_closure tables are no longer used, and can be dropped.

3. dagnabit is no longer mixed into ActiveRecord::Base by default. You need to augment the models you want to use as vertices:

    class Vertex < ActiveRecord::Base
      extend Dagnabit::Vertex::Activation
   
      acts_as_vertex
    end
   

4. The default name of the edge table is now edges, and the name of the vertex table is taken from the model.

   So, for example, if you had the following models:

    class Vertex < ActiveRecord::Base
      extend Dagnabit::Vertex::Activation
   
      acts_as_vertex
    end
   
    class BetaVertex < Vertex
    end
   
    class DifferentGraphVertex < ActiveRecord::Base
      extend Dagnabit::Vertex::Activation
   
      acts_as_vertex
      set_edge_table 'different_edges'
    end
   

   then Vertex and BetaVertex would be stored in the vertices table and use the edges table, and DifferentGraphVertex instances would be created from rows in the different_graph_vertices table and be linked with edges from the different_edges table.

5. The default edge column names have changed. ancestor_id is now parent_id and descendant_id is now child_id. ancestor_type and descendant_type are now unused.

6. Technically, you no longer need an edge model to use dagnabit. It can, however, occasionally be useful. To make an edge model, create a model resembling

   class Edge < ActiveRecord::Base
     extend Dagnabit::Edge::Activation
   
     acts_as_edge
   end