Question

I have the following module/class:

module Pigeons
  class FedEx

    attr_accessor :signature_name

    def initialize(account)
      self.account = account
    end

    def response(number)
      body = "...some xml..."
      return HTTParty.post('http://example.com', :body => body)
    end

    def track(number)
      details = response(number)

      self.signature_name = details[:delivery_signature_name]      
    end 
  end
end

What I’d like to be able to do is this:

@fedex ||= Pigeons::FedEx.new('123abc')
tracker = fedex.track('1234567890')
tracker.signature_name

Everything is working up until the tracker.signature_name part, which throws an undefined method 'signature_name' for nil:NilClass error.

Answer 1

The problem is in this line:

self.signature_name = details[:delivery_signature_name]      

details[:delivery_signature_name] turns out to be nil, which is then assigned to self.signature_name and then becomes return value of track method. And here

tracker = fedex.track('1234567890')
tracker.signature_name

tracker will be nil and you try to call a method on it.

You probably meant to write this instead:

def track(number)
  details = response(number)

  self.signature_name = details[:delivery_signature_name]      
  self # <== here
end