Unable to access the association inside a model

I have a card model,

class Card < ApplicationRecord
  has_one :meta_sm2
  after_create :add_meta

  private

  def add_meta
    self.meta_sm2.create()
  end
end

After I create a card object, I get a NoMethodError which states that create function inside add_meta does not exist becase self.meta_sm2 is nil.

class MetaSm2 < ApplicationRecord
end

Error,

NoMethodError: undefined method `create' for nil:NilClass
    from /Users/li-xinyang/Desktop/XX_API/app/models/card.rb:37:in `add_meta'

Solved

The correct way of creating an associated record is by calling create_association_name, so use create_meta_sm2:

def add_meta
  create_meta_sm2
end

More info: http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html