Comparing identical DateTime objects in ruby — why are these two DateTime.now's not equal?

Question

In a rails app, I have model code of the form:

def do_stuff(resource)
  models = Model.where(resource: resource)
  operated_at = DateTime.now

  models.each         


        

Answer 1

You have three separate methods defined above with three separate operated_at local variables. Local variables are limited to the scope of the method which defines them.

You need to define instance variables, which persist throughout a class. For example, you could:

def Model
  attr_accessor :operated_at

  def do_stuff(resource)
    models = Model.where(resource: resource)
    operated_at = DateTime.now

    models.each { |model| some_operation(model, operated_at) }

    some_other_operation models, operated_at
  end

  def some_operation(model, operated_at)
    model.date_time_field = operated_at
    model.save
  end

  def some_other_operation(models, operated_at)
    models.each do |model|
      if model.date_time_field < operated_at
        # do something
      end    
    end
  end
end  

This would enable you to access operated_at throughout all of the class methods.