How to save a model without running callbacks in Rails

Question

I need to calculate values when saving a model in Rails. So I call calculate_averages as a callback for a Survey class:

before_save         


        

Answer 1

To disable en-mass callbacks use...

Survey.skip_callback(:save, :before, :calculate_averages)

Then to enable them...

Survey.set_callback(:save, :before, :calculate_average)

This skips/sets for all instances.

Answer 2

If you want to conditionally skip callbacks after checking for each survey you can write your custom method.

For ex.

Modified callback

before_save :calculate_averages, if: Proc.new{ |survey| !survey.skip_callback }

New instance method

def skip_callback(value = false)
  @skip_callback = @skip_callback ? @skip_callback : value
end

Script to update surveys

Survey.all.each do |survey|
  survey.some_average = (survey.some_value + survey.some_other_value) / 2.to_f
  #and some more averages...
  survey.skip_callback(true)
  survey.save!
end

Its kinda hack but hope will work for you.