Module: ChronoModel::TimeMachine::HistoryModel::ClassMethods

Includes:
TimeQuery, Timeline
Defined in:
lib/chrono_model/time_machine/history_model.rb

Overview

Methods that make up the history interface of the companion History model, automatically built for each Model that includes TimeMachine

Instance Method Summary collapse

Methods included from Timeline

#has_timeline, #quoted_history_fields, #timeline, #timeline_associations, #timeline_associations_from

Instance Method Details

#as_of(time) ⇒ Object

Fetches as of time records.



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# File 'lib/chrono_model/time_machine/history_model.rb', line 74

def as_of(time)
  non_history_superclass.from(virtual_table_at(time)).as_of_time!(time)
end

#at(time) ⇒ Object

Fetches history record at the given time



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# File 'lib/chrono_model/time_machine/history_model.rb', line 87

def at(time)
  time_query(:at, time).from(quoted_table_name).as_of_time!(time)
end

#find ⇒ Object 



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# File 'lib/chrono_model/time_machine/history_model.rb', line 33

def find(*)
  with_hid_pkey { super }
end

#history? ⇒ Boolean

To identify this class as the History subclass



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# File 'lib/chrono_model/time_machine/history_model.rb', line 49

def history?
  true
end

#non_history_superclass(klass = self) ⇒ Object

Getting the correct quoted_table_name can be tricky when STI is involved. If Orange < Fruit, then Orange::History < Fruit::History (see define_inherited_history_model_for). This means that the superclass method returns Fruit::History, which will give us the wrong table name. What we actually want is the superclass of Fruit::History, which is Fruit. So, we use non_history_superclass instead. -npj



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# File 'lib/chrono_model/time_machine/history_model.rb', line 60

def non_history_superclass(klass = self)
  if klass.superclass.history?
    non_history_superclass(klass.superclass)
  else
    klass.superclass
  end
end

#of(object) ⇒ Object

Fetches the given object history, sorted by history record time by default. Always includes an “as_of_time” column that is either the upper bound of the validity range or now() if history validity is maximum.



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# File 'lib/chrono_model/time_machine/history_model.rb', line 102

def of(object)
  where(id: object)
end

#past ⇒ Object 



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# File 'lib/chrono_model/time_machine/history_model.rb', line 44

def past
  time_query(:before, :now).where("NOT upper_inf(#{quoted_table_name}.validity)")
end

#relation ⇒ Object 



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# File 'lib/chrono_model/time_machine/history_model.rb', line 68

def relation
  super.as_of_time!(Time.now)
end

#sorted ⇒ Object

Returns the history sorted by recorded_at



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# File 'lib/chrono_model/time_machine/history_model.rb', line 93

def sorted
  all.order(Arel.sql(%[ #{quoted_table_name}."recorded_at" ASC, #{quoted_table_name}."hid" ASC ]))
end

#time_query(match, time, options = {}) ⇒ Object

In the History context, pre-fill the :on options with the validity interval.



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# File 'lib/chrono_model/time_machine/history_model.rb', line 39

def time_query(match, time, options = {})
  options[:on] ||= :validity
  super
end

#virtual_table_at(time, name = nil) ⇒ Object 



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# File 'lib/chrono_model/time_machine/history_model.rb', line 78

def virtual_table_at(time, name = nil)
  name = name ? connection.quote_table_name(name) :
    non_history_superclass.quoted_table_name

  "(#{at(time).to_sql}) #{name}"
end

#with_hid_pkey(&block) ⇒ Object

HACK. find() and save() require the real history ID. So we are setting it now and ensuring to reset it to the original one after execution completes. FIXME



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# File 'lib/chrono_model/time_machine/history_model.rb', line 24

def with_hid_pkey(&block)
  old = self.primary_key
  self.primary_key = :hid

  block.call
ensure
  self.primary_key = old
end