def add
      meter = nil
      Meter.uncached { meter = Meter.find_by_name_and_created_on(name, created_on) }
      meter ||= Meter.new(name: name, created_on: created_on)
      meter.value += value
      return meter.save
    end
def add
      meter = nil
      Meter.uncached { meter = Meter.find_by_name_and_created_on(name, created_on) }
      meter ||= Meter.new(name: name, created_on: created_on)
      meter.value += value
      return meter.save
    end
Instance methods
 Create an object for this name+date in the db if one does not already exist.
 Add the value from this object to the one in the DB.
 Returns the result of the ActiveRecord save operation.