Question

I wrote an instance method in my model for calculating a time difference between two dates. Works when the second date exists, but need to add an if else condition to return a string if the second date does not exist. I have

class Incident  
def calculate_elapsed(difference)
if self.closed.nil?
  @difference = "Open"
else
  d1 = self.created
  d2 = self.closed
  difference = d2 - d1
  @difference = difference.to_i
end 

When I try to load an Incident which I know to have an empty closed date I get

You have a nil object when you didn't expect it!

You might have expected an instance of Array.

The error occurred while evaluating nil.-

Puzzled by the error because I figured if self.closed.nil?
was checking for the nil object. What can I do to get this to work?

I’m not certain this is the right way to handle what I’m trying to do, so open to any and all suggestions (i.e. this should be a class method, helper, etc. Had it in my controller previously and figured this was a step in the right direction).

What’s further confusing is that I can call this method in a partial and it returns the “Open” string wherever the closed date does not exist.

Edit

Here’s what I got working-

Model:

class Incident  
def calculate_elapsed
if self.closed.blank?
  @difference = "Complaint Open"
else
  d1 = created
  d2 = closed
  difference = d2 - d1
  difference_clean = difference.to_i
  @difference = difference_clean.to_s + ' Days'
end 
end

show.html.erb

<%= @incident.calculate_elapsed %>

_incidents.html.erb partial

<%= incident.calculate_elapsed %>

Answer 1

The error should be somewhere else, because nil? method is defined on Objects and nil is also an object.

As my last comment probably helped, possibly your class definition in you Rails environment was outdated, so restarting the application forced Rails to reload the source.

You can also reload the classes with reload! method for e.g. in Rails console.