signup_controller.rb

class SignupController < ApplicationController
  def new
    @user = User.new
  end

  def create
    @user = User.new(user_params)

    if @user.save
      redirect_to login_path,
        notice: t("flash.signup.create.notice")
    else
      render :new
    end
  end

  private
  def user_params
    params
      .require(:user)
      .permit(:name, :email, :password, :password_confirmation)
  end
end

user.rb

class User < ActiveRecord::Base
  validates_presence_of :name
  validates_format_of :email, with: /\A[a-z0-9_.+]+@[-a-z0-9.]+\.[a-z]{2,4}\z/i
  validates_uniqueness_of :email

  has_secure_password

  has_many :tasks

  def pending_tasks_count
    tasks.pending.count
  end

  def done_tasks_count
    tasks.done.count
  end
end