Added user model and fixed reference in migration

app/models/job.rb

@@ -1,4 +1,4 @@
 class Job < ApplicationRecord
-  belongs_to :operator_id
-  belongs_to :costumer_id
+  belongs_to :operator, class_name: 'User', optional: true
+  belongs_to :costumer, class_name: 'User', optional: true
 end

app/models/user.rb

@@ -0,0 +1,3 @@
+class User < ApplicationRecord
+  has_many :Jobs, foreign_key: :costumer_id
+end