Method: ActiveRecord::Persistence#touch

Defined in:

activerecord/lib/active_record/persistence.rb

#touch(*names, time: nil) ⇒ Object

Saves the record with the updated_at/on attributes set to the current time or the time specified. Please note that no validation is performed and only the after_touch, after_commit and after_rollback callbacks are executed.

This method can be passed attribute names and an optional time argument. If attribute names are passed, they are updated along with updated_at/on attributes. If no time argument is passed, the current time is used as default.

product.touch                         # updates updated_at/on with current time
product.touch(time: Time.new(2015, 2, 16, 0, 0, 0)) # updates updated_at/on with specified time
product.touch(:designed_at)           # updates the designed_at attribute and updated_at/on
product.touch(:started_at, :ended_at) # updates started_at, ended_at and updated_at/on attributes

If used along with belongs_to then touch will invoke touch method on associated object.

class Brake < ActiveRecord::Base
  belongs_to :car, touch: true
end

class Car < ActiveRecord::Base
  belongs_to :corporation, touch: true
end

# triggers @brake.car.touch and @brake.car.corporation.touch
@brake.touch

Note that touch must be used on a persisted object, or else an ActiveRecordError will be thrown. For example:

ball = Ball.new
ball.touch(:updated_at)   # => raises ActiveRecordError

# File 'activerecord/lib/active_record/persistence.rb', line 793

def touch(*names, time: nil)
  _raise_record_not_touched_error unless persisted?
  _raise_readonly_record_error if readonly?

  attribute_names = timestamp_attributes_for_update_in_model
  attribute_names = (attribute_names | names).map! do |name|
    name = name.to_s
    name = self.class.attribute_aliases[name] || name
    verify_readonly_attribute(name)
    name
  end

  unless attribute_names.empty?
    affected_rows = _touch_row(attribute_names, time)
    @_trigger_update_callback = affected_rows == 1
  else
    true
  end
end