app/models/user.rb
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :recoverable, :rememberable, :validatable, :registerable
has_and_belongs_to_many :events, :uniq => true
has_many :clients
validates :name, presence: true
validates :email, presence: true
validates_format_of :email, :with => Devise::email_regexp
end