omniauthを利用したfacebook認証が実装できない

Question

facebookでのログイン、新規登録機能を実装しようとして、新規登録のリンクを押すとターミナル上で以下のエラーが発生します。

Started GET "/users/auth/facebook/callback" for ::1 at 2019-06-29 17:40:29 +0900
I, [2019-06-29T17:40:29.628903 #65658]  INFO -- omniauth: (facebook) Callback phase initiated.
E, [2019-06-29T17:40:29.629625 #65658] ERROR -- omniauth: (facebook) Authentication failure! no_authorization_code: OmniAuth::Strategies::Facebook::NoAuthorizationCodeError, must pass either a `code` (via URL or by an `fbsr_XXX` signed request cookie)
Processing by Users::OmniauthCallbacksController#failure as HTML
Redirected to http://localhost:3000/users/sign_in
Completed 302 Found in 1ms (ActiveRecord: 0.0ms)

gem 'devise'
gem "omniauth-rails_csrf_protection"
gem 'omniauth-facebook'

= link_to 'Facebookで登録', user_facebook_omniauth_callback_path

※ちなみに
= render "devise/shared/links"
にしてクリックするとNot found. Authentication passthru.　のエラーが発生

  devise_for :users, :controllers => {
    :registrations => 'users/registrations',
    :sessions => 'users/sessions',
    :passwords => 'users/passwords',
    :omniauth_callbacks=> 'users/omniauth_callbacks'
   }

config.omniauth :facebook, "~~~~~~~(APPID)", "~~~~~~~~(KEY)"

 devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable,:omniauthable
~~~~
  def self.find_for_oauth(auth)
    user = User.where(uid: auth.uid, provider: auth.provider).first

    unless user
      user = User.create(
        uid:      auth.uid,
        provider: auth.provider,
        email:    User.dummy_email(auth),
        password: Devise.friendly_token[0, 20]
      )
    end

    user
  end

  private

  def self.dummy_email(auth)
    "#{auth.uid}-#{auth.provider}@example.com"
  end

  def resource_name
    :user
  end

  def resource
    @resource ||= User.new
  end

  def resource_class 
    User 
  end

  def devise_mapping
    @devise_mapping ||= Devise.mappings[:user]
  end

  def facebook
    callback_from :facebook
  end

  private

  def callback_from(provider)
    binding.pry
    provider = provider.to_s
    @user = User.find_for_oauth(request.env['omniauth.auth'])

    if @user.persisted?
      flash[:notice] = I18n.t('devise.omniauth_callbacks.success', kind: provider.capitalize)
      sign_in_and_redirect @user, event: :authentication
    else
      session["devise.#{provider}_data"] = request.env['omniauth.auth']
      redirect_to new_user_registration_url
    end
  end

コントローラーでbinding.pryが聞かずに、そのままリダイレクトされて新規登録画面に飛んでしまいます。

よろしくお願いいたします。

Answer 1

今更ですが、以下のようにPOSTメソッドを追加することで解決するのではないでしょうか？
参考:https://github.com/cookpad/omniauth-rails_csrf_protection
（こちらのREADMEに記載されている方法ですが）

after

= link_to 'Facebookで登録', user_facebook_omniauth_callback_path, method: :post

before

= link_to 'Facebookで登録', user_facebook_omniauth_callback_path