module Neo4j::Rails::Versioning

Adds snapshot based versioning to Neo4j Rails models To use versioning, include this module in your model.

Example:

class VersionableModel < Neo4j::Rails::Model
  include Neo4j::Rails::Versioning
end

To find out the number of versions of an instance, you can use the #current_version method.

To retrieve a snapshot of an older version, use the version method.

snapshot = instance.version(1) #Retrieves version 1.

Note that the version numbers start from 1 onwards.

The snapshot retains all the properties and relationships at the point when a versioned model is saved. The snapshot also allows you to traverse incoming and outgoing relationships.

For example:

snapshot.incoming(:friends) would return a collection of nodes that are related via the friends relationship.

The snapshot node creates relationships with a model’s related nodes with a “version_” prefix in order to avoid name clashes. However, you can call the incoming and outgoing methods using your model’s relationship names.

To control the maximum number of versions created, you can use the max_versions property.

Example:

class MaxVersionableModel < Neo4j::Rails::Model
  include Neo4j::Rails::Versioning
  max_versions 10
end

Public Instance Methods

current_version() click to toggle source

Returns the current version of a model instance

# File lib/neo4j/rails/versioning/versioning.rb, line 74
def current_version
  self._version ||= 0
end

revert_to(version_number) click to toggle source

Reverts this instance to a specified version @param [ Integer ] version_number The version number to revert to. Reverting the instance will increment the current version number.

# File lib/neo4j/rails/versioning/versioning.rb, line 102
def revert_to(version_number)
  snapshot = version(version_number)
  self.props.each_pair{|k,v| self[k] = nil if !snapshot.props.has_key?(k)}
  snapshot.props.each_pair{|k,v| self[k] = v if self.props[k].nil?}
  Neo4j::Transaction.run do
    restore_relationships(snapshot)
    save
  end
end

save() click to toggle source

Overrides Rails’s save method to save snapshots.

# File lib/neo4j/rails/versioning/versioning.rb, line 90
def save
  if self.changed? || self.relationships_changed?
    self._version = current_version + 1
    super
    revise
  end
end

version(number) click to toggle source

Returns the snapshot version for a given instance. @param [ Integer ] number The version number to retrieve. Returns nil in case a version is not found.

# File lib/neo4j/rails/versioning/versioning.rb, line 82
def version(number)
  snapshot = Version.find(:model_classname => _classname, :instance_id => neo_id, :number => number) {|query| query.first.nil? ? nil : query.first.end_node}
  snapshot.props.each_pair{|k,v| snapshot.assign(k,Neo4j::TypeConverters.to_ruby(self.class, k, v))} if !snapshot.nil?
  snapshot
end