Module: Dagnabit::Vertex::Bonding

Defined in:
lib/dagnabit/vertex/bonding.rb

Overview

Contains methods for bonding a vertex to a graph.

Instance Method Summary collapse

Instance Method Details

#bond_for(graph) ⇒ Array<edge_model>

Calculates a bond for this vertex (the method receiver) to all source vertices of ‘graph`.

This method expects the receiver to have been persisted, and will raise ‘RuntimeError` if that is not the case.

Persisted edges that already connect the receiver vertex to source vertices in ‘graph` will not be duplicated. Unpersisted edges connecting the receiver to a source in `graph` will be duplicated, so it is advised that you ensure that all vertices and edges in `graph` have been persisted before using #bond_for.

This method requires the existence of an edge model; see Settings#edge_model and Settings#edge_model_name=. If an edge model has not been set, this method raises ‘RuntimeError`.

Edges instantiated by ‘bond_for` are not automatically saved.

Parameters:

Returns:

  • (Array<edge_model>) —

    a list of edges that, when saved, will bond the vertex to ‘graph`

Raises:

  • (RuntimeError) —

    if an edge model has not been set



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# File 'lib/dagnabit/vertex/bonding.rb', line 30

def bond_for(graph)
  edge = self.class.edge_model

  raise 'edge_model must be set' unless edge
  raise "#{self} must be persisted before invoking bond_for" if new_record?

  sources = graph.sources
  existing = edge.all(:conditions => { :parent_id => id, :child_id => sources.map(&:id) }).map { |e| [e.parent_id, e.child_id] }
  new = sources.inject([]) { |es, s| es << [id, s.id] }

  (new - existing).map { |p, c| edge.new(:parent_id => p, :child_id => c) }
end