User can't be blank on Rails - ruby-on-rails

Question

Hello I am learning rails and I have made a mistake that error message shows when I submit the article but can't seem to know where the problem is. I think it's a controller?
Github files of my code:
GitHub Project
users_controller.rb
class UsersController < ApplicationController
def index
#users = User.all
end
def new
#user = User.new
end
def create
#user = User.new(user_params)
if #user.save
flash[:success] = "welcome to the alpha blog #{#user.username}"
redirect_to articles_path
else
render 'new'
end
end
def edit
#user = User.find(params[:id])
end
def update
#user = User.find(params[:id])
if #user.update(user_params)
flash[:success] = "Your account was updated successfully"
redirect_to articles_path
else
render 'edit'
end
end
def show
#user = User.find(params[:id])
end
private
def user_params
params.require(:user).permit(:username, :email, :password)
end
end
articles_controller.rb
class ArticlesController < ApplicationController
before_action :set_article, only: [:edit, :update, :show, :destroy]
# Helppppp!
def index
#articles = Article.all
end
def new
#article = Article.new
end
def edit
#article = Article.find(params[:id])
end
def create
#article = Article.new(article_params)
#article.user = User.new
if #article.save
flash[:success] = "Article was successfully created"
redirect_to article_path(#article)
else
render :new
end
end
def update
if #article.update(article_params)
flash[:success] = "Article was successfully updated."
redirect_to article_path(#article)
else
render 'edit'
end
end
def show
end
def destroy
#article.destroy
flash[:danger] = "Article was successfully deleted"
redirect_to articles_path
end
private
def set_article
#article = Article.find(params[:id])
end
def article_params
params.require(:article).permit(:title, :description)
end
end

Answer 1

Look at your method:
def create
#article = Article.new(article_params)
#article.user = User.new
...
end
You are trying to assign empty user to your article object. You should pass user_id as a param (don't forget to add it as a permitted param in article_params) and your code should be:
#article.user = User.find(article_params[:user_id])

Answer 2

Fixed it by defining current_user method in the application_controller.rb and added the following:
**application_controller.rb**
class ApplicationController < ActionController::Base
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception
helper_method :current_user, :logged_in?
def current_user
#current_user ||= User.find(session[:user_id]) if session[:user_id]
end
def logged_in?
!!current_user
end
def require_user
if !logged_in?
flash[:danger] = "You must be logged in to perform that action"
redirect_to root_path
end
end
end
articles_controller.rb
class ArticlesController < ApplicationController
before_action :set_article, only: [:edit, :update, :show, :destroy]
before_action :require_user, except: [:index, :show]
before_action :require_same_user, only: [:edit, :update, :destroy]
def index
#articles = Article.paginate(page: params[:page], per_page: 5)
end
def new
#article = Article.new
end
def edit
end
def create
#article = Article.new(article_params)
#article.user = current_user #code that needs fix
if #article.save
flash[:success] = "Article was successfully created"
redirect_to article_path(#article)
else
render :new
end
end
def update
if #article.update(article_params)
flash[:success] = "Article was successfully updated."
redirect_to article_path(#article)
else
render 'edit'
end
end
def show
end
def destroy
#article.destroy
flash[:danger] = "Article was successfully deleted"
redirect_to articles_path
end
private
def set_article
#article = Article.find(params[:id])
end
def article_params
params.require(:article).permit(:title, :description)
end
def require_same_user
if current_user != #article.user
flash[:danger] = "You can only edit or delete your own article"
redirect_to root_path
end
end
end