CODEWITHSUNDEEP
ruby-on-rails
Zephyr4434
Zephyr4434

Reputation: 796

Rails - how to perform a math function in a view helper

In my view helper method, I want to be able to calculate the range between two numbers. Right now I am doing this:

def show_range
 max = @shirts.get_max
 min = @shirts.get_min
 max-min
end

I know that max and min are working because I can just print each of their values out. However, when I try to do this simply math function in my "module ShirtsHelper", I get the following error:

undefined method `-' for nil:NilClass

Why am I getting this error and what can I do to fix it?

Upvotes: 0

Views: 837

Answers (1)

Thomas Klemm
Thomas Klemm

Reputation: 10856

You get the error because your max variable is nil and there is no matching method - on nil. You could check whether min and max are not nil with max - min if max && min. However, I guess you might want to provide a fallback value (e.g. 0) in this case, so you might be looking for something like this

def show_range
  max = @shirts.get_max
  min = @shirts.get_min

  if max && min
    max - min
  else
    0 # Fallback value
  end
end

Or even more concise:

def show_range
  max = @shirts.get_max
  min = @shirts.get_min
  max && min ? max - min : 0
end

Upvotes: 3

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