条件Rails表单验证

Question

I have a rails model that has two field attributes: :commission_fixed & :commission_percentage . The user should only be able to choose between one of the two options either: :commission_fixed or :commission_percentage not both on form submit. Is this possible using Rails validation? If so what is the best way to achieve this?

Answer 1

Your problem is within the way you've structured your column names / model attributes.

Ideally you should change your attribute names on your model to :commission_method and :commission_rate . This allows for greater flexibility. Then in your view you can achieve what you're looking for with a radio button. You can store your :commission_rate as a decimal in the db.

<%= f.radio_button :commission_method, "Fixed" %>
<%= f.radio_button :commission_method, "Percentage" %>
<%= f.number_field :commission_rate %>

In your view files if you need to switch between showing a fixed amount and a percentage you can just do:

<% case @sales_associate.commission_method %>
<% when 'Fixed' %>
  <span>Fixed: <%= number_to_currency(@sales_associate.commission_rate) %></span>
<% when 'Percentage' %>
  <span>Percentage: <%= "% #{@sales_associate.commission_rate}" %></span>
<% end %>

However, you "could" write a custom validation method that throws an error if both attributes were assigned.

In whatever model:

class SalesAssociate
   validate :only_one_selected_commission

   def only_one_selected_commission
     errors[:base] << "Please select only one form of commission" if self.commission_fixed.present? && self.commission_percentage.present?
   end
end