How to calculate difference of two fields on form submit Ruby on Rails

Question

I am new to Ruby on Rails and have been using Scaffolding. On one of the forms I want to be able to have two fields and then have the difference between the two submitted to the database.

Instead of :pickupamount, I want (Ending Amount - Starting Amount) to be calculated and entered into the pickupamount column of my database.

Thanks in advance!

Answer 1

In your view:

form_tag '/some_action' do
    text_field_tag 'start_amount'
    text_field_tag 'end_amount'
end

In your controller:

def create
    model = Model.new
    model.pickupamount = params[:end_amount].to_i - params[:start_amount].to_i
    model.save!
end