NoMethodError (undefined method `posts' for nil:NilClass): - ruby-on-rails

Question

Somebody help me pleases, I sent local server post method but happened as the above error so i tried a lot of things recreate table, changed path and model name and so on
However I couldn't slove it , I want to know how to fix it and why happed this error,
Ruby 2.5.3 Rails 6.0.0 rc2
Controller
class PostsController < ApplicationController
before_action :authenticate_user!, only: [:new]
def index
#posts = current_user.posts.all
end
def new
#post = Post.new
end
# Maybe here is happening error
def create
if #post = current_user.posts.build(posts_params)
flash[:success] = "You created post"
redirect_to #posts
else
flash[:failed] = "You failed posted "
end
end
def edit
end
def show
end
private
def posts_params
params.require(:posts).permit(:title , :content , :user_id)
end
end
Routes
Rails.application.routes.draw do
devise_for :users , :paths => 'users'
resources :users do
resources :posts , :except => :edit
end
root 'users#index'
end
User model
class User < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable,
:authentication_keys => [:name]
validates :name, presence: true, uniqueness: true , length:{maximum: 10}
has_many :posts
Thanks everyone, It seems to be problem is current_user
So, I use byebug so that (byebug) current_user
User Load (0.5ms) SELECT users.* FROM users WHERE users.id = 1 ORDER BY users.id ASC LIMIT 1
↳ (byebug):1:in `create'
Again thanks everyone, I rewrote code
class PostsController < ApplicationController
before_action :authenticate_user!, only: [:index, :new, :create]
def index
#posts = current_user.posts.all
end
def new
#post = Post.new
end
def create
if #post = current_user.posts.create(posts_params)
flash[:success] = "You created post"
redirect_to user_posts_path
else
flash[:failed] = "You failed posted "
end
end
def edit
end
def show
end
private
def posts_params
params.require(:posts).permit(:title , :content , :user_id)
end
end
Sadly this code also doesn't work , just in case , i wrote form code
<%= form_with model: #post , url: user_posts_path ,local: true do |f| %>
<%= f.label :title %>
<%= f.text_field :title %>
<%= f.label :content %>
<%= f.text_area :content %>
<% f.label :user_id %>
<% f.hidden_field :user_id %>
<%= f.submit "Create Post" %>

Answer 1

In your Controller, you only require user to login for action new. This causes every other page user can visit / interact without authentication.
So, with your controller code, you will get the error undefined posts for nil if there's no logged in user with this call current_user.posts
class PostsController < ApplicationController
before_action :authenticate_user!, only: [:new]
def index
#posts = current_user.posts.all
end
def new
end
def create
if #post = current_user.posts.build(posts_params)
# ...
end
end
def edit
end
def show
end
end
To fix this error, you can add more actions requiring user authentication
class PostsController < ApplicationController
before_action :authenticate_user!, only: [:index, :new, :create]
end
or just require it for all actions of the controller
class PostsController < ApplicationController
before_action :authenticate_user!
end

Answer 2

There are several errors in the code:
Check user for create action
before_action :authenticate_user!, only: %i[new create]
Use create method instead of build method and fix redirect problem.
def create
if #post = current_user.posts.create(posts_params)
flash[:success] = "You created post"
redirect_to #post
else
flash[:failed] = "You failed posted"
end
end
However, if you get an error, check the devise configuration for current_user.

Answer 3

Change from
class PostsController < ApplicationController
before_action :authenticate_user!, only: [:new]
end
to
class PostsController < ApplicationController
before_action :authenticate_user!
end
Because you call current_user in index action, and basically I think all the actions requires user to log in.