gistfile1.rb

class ErrorInstance
 def self.create_from(email)
   
   #your other create_from code
   
   #ActiveRecord block initialization
 error_instance = ErrorInstance.new do |instance|
    instance.error_id = Error.find_or_create(exception).id
    instance.exception = exception
    #etc, your other parameters go here
  end
  error_instance.save
  
  # I'm not certain this needs to be returned. It might not, depending on how
  # you end up implementing search. 
  return error_intsance
  
  end
 end
  
  class Error
   
  def most_recent_instance
   ErrorInstance.order("timestamp").find_by(error_id: this.id)
  end
  
   
    def self.find_or_create(exception)
     
      # try to find an error
      error = Error.first(exception: exception)
      
      # if we fail, create a new error
      # It's possible Rails 4 ActiveRecord doesn't return 'nil' if no
      # record is found on first. If not, this conditional will need
      # to be changed a bit.
      unless error do
        #ActiveRecord hash initilization to create a new Error
        error = Error.new(name: exception)
        error.save
      end
      
      #return the error
      error
    end
  end