Rails Convert Percentage Value on Edit Form

问题:

I have the following callback and method in my Customer model.

before_save :convert_commission_percentage

def convert_commission_percentage
  self.commission= commission.to_f/100.to_f
end

This allows the user to input a percentage as 45 and store it as .45. However, on edit, the field for this percentage is then displayed as .45 on the edit form, causing that number to be divided by 100 again on update. Is there a way to keep this from happening by displaying the edit field as 45?

回答1:

There are a few options:

1. Why store converted value, why not store whatever the user inputs without modification. commission_percentage might be a better name. You could create an alias commission to commission_percentage with alias_attribute :commission, :commission_percentage if you'd like to use commission attribute instead of commission_percentage attribute in your application.

2. Using after_initialize callback:

   before_save :convert_commission_percentage
   
   after_initialize do 
     commission = commission.to_f * 100
   end
   
   def convert_commission_percentage
     self.commission= commission.to_f/100.to_f
   end
   

3. Through getters and setters:

   def commission=(value)
     write_attribute :commission, value.to_f/100
   end
   
   def commision
     read_attribute(:commission).to_f * 100
   end