ActionController::ParameterMissing param is missing or the value is empty - ruby-on-rails

Question

I can't solve this problem.
When I try to use "Chatroom#new" method, I I got this error, ActionController::ParameterMissing param is missing or the value is empty .
below codes are the ChatroomController.
class ChatroomsController < ApplicationController
before_action :find_room_owner,only:[:index]
before_action :objects_for_index,only:[:index]
def index
#/users/:user_id/cart/items/chatroom
sign_in #user if signed_in?
if #seller && #buyer
flash[:success] = "U are owners of the chatroom"
#messages = Message.all #Messageのmodelを作成
else
flash[:error] = "U cant enter the chatroom."
redirect_to user_cart_items_url(#user,#cart,#items) ##user,#cart,#itemsをgetしろ
end
end
def new
#user = User.find(params[:user_id])
#cart = Cart.find(params[:user_id])
#item = Item.find(params[:item_id])
#message = Message.new(message_params)
end
def create
#user = User.find(params[:user_id])
#message = #user.messages.build
if #message.save
#message.update_attributes(user_id:#user.id)
redirect_to user_cart_chatroom_path(#user,#cart,#items)
else
flash[:error] = "could not create any message."
render 'new'
end
end
private
def message_params
params.require(:messages).permit(:id,:user_id,:messages)
#params{:message => :id,:user_id,:messages}
end
#before_aciton
def find_room_owner
#item = Item.find(params[:item_id])
#buyer = User.find(params[:user_id])
#seller = Product.find_by(user_id:#item.user_id)
end
def objects_for_index
#user = User.find(params[:user_id])
#items = Item.all
end
end
Below codes are the view of Message#new.
<h1>Chatroom#new</h1>
<p>Find me in app/views/chatroom/new.html.erb</p>
<%= form_for #message,url:new_user_cart_item_chatroom_path(#user,#cart,#item) do |f| %>
<%= f.label :messages %>
<%= f.text_field :messages %>
<%= f.submit "new message", class:"btn btn-default" %>
<% end %>
Below codes are the migration of Message.
class CreateMessages < ActiveRecord::Migration
def change
create_table :messages do |t|
t.integer :user_id
t.string :messages
t.timestamps
end
end
end
Below codes are the model of message.
class Message < ActiveRecord::Base
validates :messages,presence:true,length:{maximum:200}
belongs_to :user
end
Below codes are the routes.
KaguShop::Application.routes.draw do
resources :users,only:[:show,:new,:create,:edit,:update,:destroy] do
collection do
get 'get_images',as:'get_images'
end
resources :products,only:[:show,:index,:new,:create,:edit,:update,:destroy] do
collection do
post 'add_item', as:'add_item'
get 'get_image',as:'get_image'
get 'get_images',as:'get_images'
end
end
end
resources :users,only:[:show,:new,:create,:edit,:update,:destroy] do
resource :cart,except:[:new,:show,:edit,:destroy,:update,:create] do
collection do
post 'purchase', as:'purchase'
#get 'show' , as: 'show'
post 'create' , as: 'create'
#多分routeにas的な感じでtemplateを提供するのが一番いい気がする
delete 'destroy',as:'destroy'
delete 'remove_item',as:'remove_item'
end
resources :items,only:[:show,:index] do
collection do
get 'get_images',as:'get_images'
end
resources :chatrooms,only:[:index,:create,:new] do
end
end
end
end
resources :sessions,only:[:new,:create,:destroy]
root 'products#index'
match '/signup', to:'users#new',via:'get'
match '/signin', to:'sessions#new', via:'get'
match '/signout', to:'sessions#destroy', via:'delete'
match '/contact', to:'nomal_pages#contact', via:'get'
end

Answer 1

You should call Message.new without params because message_params nil in this request and this raise ActionController::ParameterMissing:
class ChatroomsController < ApplicationController
#.........
def new
#user = User.find(params[:user_id])
#cart = Cart.find(params[:user_id])
#item = Item.find(params[:item_id])
#message = Message.new
end
#........
private
def message_params
params.require(:messages).permit(:id,:user_id,:messages)
end
#.......
end