Q:

Why signing in doesn't work?

When I'm trying to sign in with an actual user information who's already in database, an error's being rendered "Invalid email/password confirmation.", however it's not supposed.
Why is that?
controllers/sessions_controller.rb
class SessionsController < ApplicationController
  def new
  end

  def create
    user = User.authenticate(params[:session][:email], params[:session][:password])

    if user.nil?
      flash.now[:error] = "Invalid email/password confirmation."
      render :new
    else
      sign_in user
      redirect_to user
    end
  end 

  def destroy
    sign_out
    redirect_to signin_path
  end
end

app/views/sessions/new.html
<h1>Sign in</h1>

    <% if flash[:error] %>
       <p><%= flash[:error] %></p>
    <% end %>

    <%= simple_form_for(:session, url: sessions_path) do |f| %>

      <%= f.input :email %>

      <%= f.input :password%>

      <%= f.button :submit %>

    <% end %>

    <p>New user? <%= link_to "Sign up now!", signup_path %></p>

app/helpers/sessions_helper.rb
module SessionsHelper

  def sign_in(user)
    session[:user_id] = user.id
    self.current_user = user
  end

  def current_user=(user)
    @current_user = user
  end

  def current_user
    if session[:user_id]
    @current_user ||= User.find(session[:user_id])
    end
  end

  def signed_in?
    !current_user.nil?
  end

  def sign_out
    session[:user_id] = nil
    self.current_user = nil
  end

  def current_user?(user)
    user == current_user
  end

  def deny_access
    redirect_to signin_path, notice: "Please sign in to access this page."
  end

end

models/user.rb
class User < ActiveRecord::Base
 has_many :tasks

  attr_accessor :password, :salt, :encrypted_password
  EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :first_name, presence: true,
            length: {maximum: 20}
  validates :last_name,  presence: true,
            length: {maximum: 40}
  validates :email, presence: true,
            format: {with: EMAIL_REGEX},
            uniqueness:  {case_sensitive: false}
  validates :password, presence: true,
            confirmation: true,
            length: {within: 6..40}

  before_save :encrypt_password

  def has_password?(submitted_password)
    encrypted_password == encrypt(submitted_password)
  end

  def self.authenticate(email, submitted_password)
    user = find_by_email(email)

    return nil if user.nil?
    return user if user.has_password?(submitted_password)
  end

  private
    def encrypt_password
      self.salt = Digest::SHA2.hexdigest("#{Time.now.utc}--#{password}")

      self.encrypted_password = encrypt(password)
    end

    def encrypt(pass)
      Digest::SHA2.hexdigest("#{self.salt}--#{pass}")
    end

  end

Can somebody help?

A:

From your code, what I see is there is a confirmation :true for password but you don't have password_confirmation field in your form. Try including it
<%= f.input :password_confirmation %> 
and also include it as attr_accessor in User model.
If you don't want a confirmation field for password, then remove confirmation: true for password in validations.
validates :password, presence: true, length: {within: 6..40}

