Q:

undefined method `number' for nil:NilClass

I am having problems display an attribute in a belongs_to relationship.  Lease belongs_to Unit.  Unit has a column "number" in the db.  When I try to display this attribute on the lease show page, it gives me an error of undefined method `number' for nil:NilClass.  I feel like I'm doing something stupid and over looking it. 
lease.rb
belongs_to :unit

unit.rb
has_many :leases

leases_controller.rb
  def show
    @lease = Lease.find(params[:id])
  end

views/leases/show.html.erb
<%= @lease.unit.number %>

If I change my show page code to @lease.unit_id it will show the id of the unit.  Here is a pic of my data base showing the Unit_id. 

A:

Your model may have unit_id attribute, but how about units that does not have that record with id = 1 have You checked? 
Quick (dirty) fix:
<%= @lease.unit.number unless @lease.unit.nil? % >

