Rails calculate the difference between two datetimes in seconds and converting to integer

Question

I am trying to set :total_time to the difference between 2 datetime items (:start_time and :end_time) in seconds. I can get the value that I want in the view by doing the following

<%= (@result.end_time.minus_with_coercion(@result.start_time)).round %>

but now I need to populate :total_time with this value when creating @result in the controller - I have tried the following:

def finish 
  @a_hill = AHill.find(params[:hill_id])
  @finish_time = Result.create(:user_id => params[:user_id], :a_hill_id => params[:hill_id], :start_time =>@a_hill.start_time, :end_time=>Time.now, :total_time=>(Time.now.minus_with_coercion(@a_hill.start_time)).round)
  if @finish_time.save
    redirect_to(:action => "race", :id =>params[:hill_id] , :hill_id =>params[:hill_id])
  end
end

or to focus on the main part of that:

:total_time=>(Time.now.minus_with_coercion(@a_hill.start_time)).round

But i get the error

"TypeError in AHillsController#finish - can't convert String into an exact number"

:total_time is an integer :start_time and :end_time are datetimes

I'm pretty new to Rails so sorry if the answer is something very obvious and thanks in advance.

Answer 1

What you need is to transform @a_hill 's start_time to a Datetime object try @a_hill.start_time.to_datetime or even better change the AHill object to have datetime objects in the start_time attribute.