问Rails 4身份验证从头开始: before_create vs before_save

EN

include MembersHelper

class Member < ActiveRecord::Base
include ActiveModel::Validations

has_many :parents, through: :reverse_relationships, source: :parent
has_many :children, through: :relationships, source: :child
has_many :relationships, foreign_key: "parent_id", dependent: :destroy
has_many :reverse_relationships, foreign_key: "child_id", class_name: Relationship, dependent: :destroy
has_many :spouses, through: :spouse_relationships, source: :spouse
has_many :spouse_relationships, foreign_key: "member_id", dependent: :destroy
has_many :images

accepts_nested_attributes_for :parents, reject_if: proc { |attributes| attributes['first_name'].blank? && attributes['first_name'].blank? }
accepts_nested_attributes_for :spouses, reject_if: proc { |attributes| attributes['first_name'].blank? && attributes['first_name'].blank? }
accepts_nested_attributes_for :children, reject_if: proc { |attributes| attributes['first_name'].blank? && attributes['first_name'].blank? }

attr_accessor :password

#####
before_save :encrypt_password ##### this does not work if i change it to before_create
#####
before_save :nil_or_downcase
before_create :nil_or_downcase
after_create :set_oldest_ancestor
before_create { create_token(:remember_token) }

before_destroy [ :set_ancestor_for_children, :destroy_spouse_id_of_spouse ]

def encrypt_password
    if password.present?
        self.password_salt = BCrypt::Engine.generate_salt
        self.password_hash = BCrypt::Engine.hash_secret( password, password_salt)
    end
end