Cannot retrieve attr_accessor in Rails 4 - ruby-on-rails

Question

I'm working on a Ruby on Rails project and I have two models:
1. User
2. Merchant
their relationships are:
User has_one :merchant
Merchant belongs_to :user
then in my user.rb
attr_accessor :merchant_name
after_create :create_merchant
def create_merchant
create_merchant(name: merchant_name)
end
In my user's form:
= form_for #user do |f|
= f.text_field :merchant_name
= f.text_field :email
= f.text_field :password
the problem is the user and a merchant has been created but the merchant's name is nil
In my Account::RegistrationsController
class Account::RegistrationsController < Devise::RegistrationsController
protected
def after_sign_up_path_for(resource)
account_users_path
end
private
def registration_params
params.require(:user).permit(:merchant_name)
end
end
I'm getting this error:
Processing by Account::RegistrationsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"ht8vHG8I4bz2ylt+mtLC7hilQnK3VnYtcHgSNv8nSeg=", "user"=>{"merchant_name"=>"Zara 123", "email"=>"allen.chun#hotmail.com",
"password"=>"[FILTERED]",
"password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign Up"}
Unpermitted parameters: merchant_name

Answer 1

I wouldn't override the create_merchant method if I were you, try something like this:
after_create -> { create_merchant!(:name => self.merchant_name) }
and make sure your merchant_name is permitted in the users controller, something like this:
def create
#user = User.new(user_params)
if #user.save
redirect_to #user
else
render :new
end
end
private
def user_params
params.require(:user).permit(:merchant_name, :email, :password, :password_confirmation)
end

Answer 2

Perhaps it should be
attr_accessor :merchant_name
after_create :create_merchant
def create_merchant
build_merchant(name: merchant_name)
save
end
create_association hasn't supported in rails 4
Also don't forget to permit merchant_name. According to this info:
class Account::RegistrationsController < Devise::RegistrationsController
before_action :configure_permitted_parameters
protected
def after_sign_up_path_for(resource)
account_users_path
end
def configure_permitted_parameters
devise_parameter_sanitizer.for(:sign_up) << :merchant_name
end
end