Module: ChronoModel::TimeMachine

Extended by:
ActiveSupport::Concern
Defined in:
lib/chrono_model/time_machine.rb

Defined Under Namespace

Modules: ClassMethods, HistoryMethods, QueryMethods, TimeQuery

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.chrono_models ⇒ Object

Returns an Hash keyed by table name of ChronoModels



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

def self.chrono_models
  (@chrono_models ||= {})
end

.define_history_model_for(model) ⇒ Object 



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# File 'lib/chrono_model/time_machine.rb', line 37

def self.define_history_model_for(model)
  history = Class.new(model) do
    self.table_name = [Adapter::HISTORY_SCHEMA, model.table_name].join('.')

    extend TimeMachine::HistoryMethods

    # The history id is `hid`, but this cannot set as primary key
    # or temporal assocations will break. Solutions are welcome.
    def id
      hid
    end

    # Referenced record ID.
    #
    def rid
      attributes[self.class.primary_key]
    end

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

      block.call
    ensure
      self.primary_key = old
    end

    def self.find(*)
      with_hid_pkey { super }
    end

    if RUBY_VERSION.to_f < 2.0
      # PLEASE UPDATE YOUR RUBY <3
      #
      def save_with_pkey(*)
        self.class.with_hid_pkey { save_without_pkey }
      end

      def save_with_pkey!(*)
        self.class.with_hid_pkey { save_without_pkey! }
      end

      alias_method_chain :save, :pkey
    else
      def save(*)
        self.class.with_hid_pkey { super }
      end

      def save!(*)
        self.class.with_hid_pkey { super }
      end
    end

    # Returns the previous history entry, or nil if this
    # is the first one.
    #
    def pred
      return if self.valid_from.nil?

      if self.class.timeline_associations.empty?
        self.class.where('id = ? AND upper(validity) = ?', rid, valid_from).first
      else
        super(:id => rid, :before => valid_from, :table => self.class.superclass.quoted_table_name)
      end
    end

    # Returns the next history entry, or nil if this is the
    # last one.
    #
    def succ
      return if self.valid_to.nil?

      if self.class.timeline_associations.empty?
        self.class.where('id = ? AND lower(validity) = ?', rid, valid_to).first
      else
        super(:id => rid, :after => valid_to, :table => self.class.superclass.quoted_table_name)
      end
    end
    alias :next :succ

    # Returns the first history entry
    #
    def first
      self.class.where(:id => rid).order('lower(validity)').first
    end

    # Returns the last history entry
    #
    def last
      self.class.where(:id => rid).order('lower(validity)').last
    end

    # Returns this history entry's current record
    #
    def current_version
      self.class.non_history_superclass.find(rid)
    end

    def record #:nodoc:
      ActiveSupport::Deprecation.warn '.record is deprecated in favour of .current_version'
      self.current_version
    end

    def valid_from
      validity.first
    end

    def valid_to
      validity.last
    end

    def recorded_at
      Conversions.string_to_utc_time attributes_before_type_cast['recorded_at']
    end
  end

  model.singleton_class.instance_eval do
    define_method(:history) { history }
  end

  history.singleton_class.instance_eval do
    define_method(:sti_name) { model.sti_name }
  end

  model.const_set :History, history

  return history
end

.define_inherited_history_model_for(subclass) ⇒ Object 



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# File 'lib/chrono_model/time_machine.rb', line 170

def self.define_inherited_history_model_for(subclass)
  # Define history model for the subclass
  history = Class.new(subclass.superclass.history)
  history.table_name = subclass.superclass.history.table_name

  # Override the STI name on the history subclass
  history.singleton_class.instance_eval do
    define_method(:sti_name) { subclass.sti_name }
  end

  # Return the subclass history via the .history method
  subclass.singleton_class.instance_eval do
    define_method(:history) { history }
  end

  # Define the History constant inside the subclass
  subclass.const_set :History, history
end

Instance Method Details

#as_of(time) ⇒ Object

Returns a read-only representation of this record as it was time ago. Returns nil if no record is found.



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# File 'lib/chrono_model/time_machine.rb', line 192

def as_of(time)
  _as_of(time).first
end

#as_of!(time) ⇒ Object

Returns a read-only representation of this record as it was time ago. Raises ActiveRecord::RecordNotFound if no record is found.



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# File 'lib/chrono_model/time_machine.rb', line 199

def as_of!(time)
  _as_of(time).first!
end

#as_of_time ⇒ Object

Read the virtual ‘as_of_time’ attribute and return it as an UTC timestamp.



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# File 'lib/chrono_model/time_machine.rb', line 233

def as_of_time
  Conversions.string_to_utc_time attributes_before_type_cast['as_of_time']
end

#changes_against(ref) ⇒ Object

Returns the differences between this record and an arbitrary reference record. The changes representation is an hash keyed by attribute whose values are arrays containing previous and current attributes values - the same format used by ActiveModel::Dirty.



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# File 'lib/chrono_model/time_machine.rb', line 306

def changes_against(ref)
  self.class.attribute_names_for_history_changes.inject({}) do |changes, attr|
    old, new = ref.public_send(attr), self.public_send(attr)

    changes.tap do |c|
      changed = old.respond_to?(:history_eql?) ?
        !old.history_eql?(new) : old != new

      c[attr] = [old, new] if changed
    end
  end
end

#current_version ⇒ Object

Returns the current history version



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# File 'lib/chrono_model/time_machine.rb', line 289

def current_version
  self.historical? ? self.class.find(self.id) : self
end

#destroy ⇒ Object

Inhibit destroy of historical records

Raises:

  • (ActiveRecord::ReadOnlyRecord) 


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# File 'lib/chrono_model/time_machine.rb', line 239

def destroy
  raise ActiveRecord::ReadOnlyRecord, 'Cannot delete historical records' if historical?
  super
end

#historical? ⇒ Boolean

Returns a boolean indicating whether this record is an history entry.

Returns:

  • (Boolean) 


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# File 'lib/chrono_model/time_machine.rb', line 227

def historical?
  self.attributes.key?('as_of_time') || self.kind_of?(self.class.history)
end

#history ⇒ Object

Return the complete read-only history of this instance.



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# File 'lib/chrono_model/time_machine.rb', line 214

def history
  self.class.history.of(self)
end

#last_changes ⇒ Object

Returns the differences between this entry and the previous history one. See: changes_against.



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# File 'lib/chrono_model/time_machine.rb', line 296

def last_changes
  pred = self.pred
  changes_against(pred) if pred
end

#pred(options = {}) ⇒ Object

Returns the previous record in the history, or nil if this is the only recorded entry.



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# File 'lib/chrono_model/time_machine.rb', line 247

def pred(options = {})
  if self.class.timeline_associations.empty?
    history.order('upper(validity) DESC').offset(1).first
  else
    return nil unless (ts = pred_timestamp(options))
    self.class.as_of(ts).order(%[ #{options[:table] || self.class.quoted_table_name}."hid" DESC ]).find(options[:id] || id)
  end
end

#pred_timestamp(options = {}) ⇒ Object

Returns the previous timestamp in this record’s timeline. Includes temporal associations.



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# File 'lib/chrono_model/time_machine.rb', line 259

def pred_timestamp(options = {})
  if historical?
    options[:before] ||= as_of_time
    timeline(options.merge(:limit => 1, :reverse => true)).first
  else
    timeline(options.merge(:limit => 2, :reverse => true)).second
  end
end

#succ(options = {}) ⇒ Object

Returns the next record in the history timeline.



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# File 'lib/chrono_model/time_machine.rb', line 270

def succ(options = {})
  unless self.class.timeline_associations.empty?
    return nil unless (ts = succ_timestamp(options))
    self.class.as_of(ts).order(%[ #{options[:table] || self.class.quoted_table_name}."hid" DESC ]).find(options[:id] || id)
  end
end

#succ_timestamp(options = {}) ⇒ Object

Returns the next timestamp in this record’s timeline. Includes temporal associations.



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# File 'lib/chrono_model/time_machine.rb', line 280

def succ_timestamp(options = {})
  return nil unless historical?

  options[:after] ||= as_of_time
  timeline(options.merge(:limit => 1, :reverse => false)).first
end

#timeline(options = {}) ⇒ Object

Returns an Array of timestamps for which this instance has an history record. Takes temporal associations into account.



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# File 'lib/chrono_model/time_machine.rb', line 221

def timeline(options = {})
  self.class.history.timeline(self, options)
end