Module: Neo4jAncestry::ActiveRecordAdditions

Defined in:
lib/models/neo4j_ancestry/active_record_additions.rb

Instance Method Summary collapse

Instance Method Details

#attributes_to_copy_to_neo4j(&block) ⇒ Object

Attributes to copy over to the neo4j database. This is just a wrapper for the ‘neoidable’ method of the neoid gem.

https://github.com/elado/neoid

Example:

attributes_to_copy_to_neo4j do |c|
  c.field :name
  c.field :name_length do 
    self.name.length
  end
end



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# File 'lib/models/neo4j_ancestry/active_record_additions.rb', line 94

def attributes_to_copy_to_neo4j(&block)
  neoidable(&block)
end

#has_many_for_rails_3_and_4(association_name, conditions_hash, options) ⇒ Object

The has_many method changes from Rails 3 to Rails 4. Since this gem supports both rails versions, this method is a wrapper.



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# File 'lib/models/neo4j_ancestry/active_record_additions.rb', line 102

def has_many_for_rails_3_and_4(association_name, conditions_hash, options)
  if Rails.version.start_with? "4"
    has_many(association_name, -> { where conditions_hash }, options)
  elsif Rails.version.start_with? "3"
    has_many(association_name, options.merge({conditions: conditions_hash}))
  end
end

#has_neo4j_ancestry(options) ⇒ Object

Example options:

parent_class_names: %w(Group), 
child_class_names: %w(Group User)



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# File 'lib/models/neo4j_ancestry/active_record_additions.rb', line 9

def has_neo4j_ancestry(options)
  
  link_class_name = 'Neo4jAncestry::Link'
  
  # Links (direct relationships between objects) are stored
  # via ActiveRecord in the mysql database. (The neo4j database contains only 
  # redundant information and is used for fast queries.)
  #
  has_many :links_as_parent, foreign_key: :parent_id, class_name: link_class_name
  has_many :links_as_child, foreign_key: :child_id, class_name: link_class_name
  
  parent_class_names = options[:parent_class_names] || []
  child_class_names = options[:child_class_names] || []
  
  # links_as_child for specific parent object classes and
  # links_as_parent for specific child object classes, e.g.
  #   group.links_as_child_for_groups
  #   group.links_as_parent_for_groups
  #   group.links_as_parent_for_users
  #
  parent_class_names.each do |parent_class_name|
    has_many_for_rails_3_and_4(
      "links_as_child_for_#{parent_class_name.underscore.pluralize}".to_sym,
      { parent_type: parent_class_name },
      { as: :child, class_name: link_class_name } )
  end
  child_class_names.each do |child_class_name|
    has_many_for_rails_3_and_4( 
      "links_as_parent_for_#{child_class_name.underscore.pluralize}".to_sym, 
      { child_type: child_class_name },
      { as: :parent, class_name: link_class_name } )
  end
  
  # parent and child associations for specific object classes, e.g.
  #   group.parent_groups
  #   group.child_groups
  #   group.child_users
  #
  parent_class_names.each do |parent_class_name|
    has_many( 
      "parent_#{parent_class_name.underscore.pluralize}".to_sym, 
      through: "links_as_child_for_#{parent_class_name.underscore.pluralize}".to_sym, 
      as: :structureable, 
      foreign_key: :parent_id, source: 'parent', 
      source_type: parent_class_name )
  end
  child_class_names.each do |child_class_name|
    has_many( 
      "child_#{child_class_name.underscore.pluralize}".to_sym, 
      through: "links_as_parent_for_#{child_class_name.underscore.pluralize}".to_sym, 
      as: :structureable, 
      foreign_key: :child_id, source: 'child', 
      source_type: child_class_name )
  end
  
  # Use the neoid gem to have this object represented as node
  # in the neo4j graph database.
  # 
  include Neoid::Node
  
  # Copy the name attribute to the neo4j nodes.
  # Other attributes can be copied as well by using the 'attributes_to_copy_to_neo4j'.
  # 
  attributes_to_copy_to_neo4j do |c|
    c.field :name
  end
  
  # Include the instance methods for interaction with the neo4j graph.
  #
  include Neo4jAncestry::NodeInstanceMethods
  
end