title: 1 error prohibited this user from being saved:Password can't be blank
body: <p>When I do lesson6 of Rails Tutorial (by Michael Hartl),there is a problem:1 error prohibited this user from being saved:Password can't be blank.</p>
  
  <p>gem 'bcrypt-ruby'</p>
  
  <p>This is my User model</p>
  
  <pre><code>   class User &lt; ActiveRecord::Base
    has_many :microposts
    attr_accessor  :name ,:email
    VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
    validates :name,  presence: true, length: { maximum: 50 }
    validates :email, presence: true , format: { with: VALID_EMAIL_REGEX }
    before_save { self.email = email.downcase }
    has_secure_password
  end
  </code></pre>
  
  <p>I've created user and now appears</p>
  
  <pre><code> Processing by UsersController#create as HTML
    Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"4TpdKJZ3BeSxpH4pWUK4L1LwzBvJmBo/4MHnYlGQsmQ=", "user"=&gt;{"name"=&gt;"tom", "email"=&gt;"tom@gmail.com", "password"=&gt;"[FILTERED]", "password_confirmation"=&gt;"[FILTERED]"}, "commit"=&gt;"Create User"}
  
  Unpermitted parameters: password, password_confirmation
  </code></pre>
  
  <p>The User  Controller</p>
  
  <pre><code>  class UsersController &lt; ApplicationController
        before_action :set_user, only: [:show, :edit, :update, :destroy]
  
        # GET /users
        # GET /users.json
        def index
          @users = User.all
        end
  
        # GET /users/1
        # GET /users/1.json
        def show
        end
  
        # GET /users/new
        def new
          @user = User.new
        end
  
        # GET /users/1/edit
        def edit
        end
  
        # POST /users
        # POST /users.json
        def create
          @user = User.new(user_params)
  
          respond_to do |format|
            if @user.save
              format.html { redirect_to @user, notice: 'User was successfully created.' }
              format.json { render action: 'show', status: :created, location: @user }
            else
              format.html { render action: 'new' }
              format.json { render json: @user.errors, status: :unprocessable_entity }
            end
          end
        end
  
        # PATCH/PUT /users/1
        # PATCH/PUT /users/1.json
        def update
          respond_to do |format|
            if @user.update(user_params)
              format.html { redirect_to @user, notice: 'User was successfully updated.' }
              format.json { head :no_content }
            else
              format.html { render action: 'edit' }
              format.json { render json: @user.errors, status: :unprocessable_entity }
            end
          end
        end
  
        # DELETE /users/1
        # DELETE /users/1.json
        def destroy
          @user.destroy
          respond_to do |format|
            format.html { redirect_to users_url }
            format.json { head :no_content }
          end
        end
  
        private
          # Use callbacks to share common setup or constraints between actions.
          def set_user
            @user = User.find(params[:id])
          end
  
          # Never trust parameters from the scary internet, only allow the white list through.
          def user_params
            params.require(:user).permit(:name, :email)
          end
      end
  </code></pre>
  
  <p>How to solve this problem "Unpermitted parameters"?   thanks</p>