How to format interpolation within error message string

Question

I have a method in my model that does the following:

def price_estimate_range
  if self.upper_price_estimate > self.lower_price_estimate + (lower_price_estimate * (1/10.0))
    errors.add(:base, "Your upper price estimate must not exceed 10% of the lower price estimate. That is #{self.lower_price_estimate + (self.lower_price_estimate * (1/10.0))}")
  end
end

How do I format the interpolation: #{self.lower_price_estimate + (self.lower_price_estimate * (1/10.0))} within the string with number_to_percentage or something similar when it's rendered in my message block?

<% @bid.errors.full_messages.each do |message| %>
  <li><%= message %></li>
<% end %>

Answer 1

def price_estimate_range
  limit = self.lower_price_estimate + (lower_price_estimate * (1/10.0))
  if self.upper_price_estimate > limit
    text = number_with_precision(limit, precision: 2)
    errors.add(:base, "Your upper price estimate must not exceed 10% of the lower price estimate. That is #{text}")
  end
end

Or sprintf the limit, or something like that. (if you might have to use that value more than once, calc it one and reuse the result)