Module: TemporalTables::HistoryHook

Defined in:
lib/temporal_tables/history_hook.rb

Overview

This hooks in a “history” method to ActiveRecord::Base which will return the class’s History class. The history class extends the original class, but runs against the history table to provide temporal results.

class Person < ActiveRecord::Base
  attr_accessible :name
end

Person         #=> Person(id: integer, name: string)
Person.history #=> PersonHistory(history_id: integer, id: integer,
                   name: string, eff_from: datetime, eff_to: datetime)

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object

rubocop:disable Metrics/MethodLength, Metrics/AbcSize



16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
 
# File 'lib/temporal_tables/history_hook.rb', line 16

def self.included(base) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
  base.class_eval do
    # Return this class's history class.
    # If it doesn't exist yet, create and initialize it, as well
    # as all dependent classes (through associations).
    def self.history # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
      raise "Can't view history of history" if name =~ /History$/

      history_class = "#{name}History"
      history_class.constantize
    rescue NameError
      # If the history class doesn't exist yet, create it
      new_class = Class.new(self) do
        include TemporalTables::TemporalClass
      end
      segments = history_class.split('::')
      object_class = segments[0...-1].inject(Object) { |o, s| o.const_get(s) }
      object_class.const_set segments.last, new_class

      # Traverse associations and make sure they have
      # history classes too.
      history_class.constantize.temporalize_associations!
      history_class.constantize
    end
  end
end

Instance Method Details

#history ⇒ Object

Returns a scope for the list of all history records for this particular object.



45
46
47
48
49
 
# File 'lib/temporal_tables/history_hook.rb', line 45

def history
  clazz = is_a?(TemporalTables::TemporalClass) ? self.class : self.class.history
  oid = is_a?(TemporalTables::TemporalClass) ? orig_class.primary_key : self.class.primary_key
  clazz.unscoped.where(oid => attributes[oid]).order(:eff_from)
end