你能帮我理解为什么这个布尔方法返回 false 吗？

Question

我有一个 User 模型，其 account_type 属性为 "Student" 或 "Partner"。我在我的用户模型中创建了布尔方法来确定用户记录是学生还是合作伙伴（见下文）。

 def student?
    self.account_type == "Student"
  end

  def partner?
    self.account_type == "Partner"
  end

在 rails 控制台中，当我将 user 设置为具有学生帐户类型的 User 实例并输入 user.account_type == "Student" 时，我得到了 true，但是当我调用 user.student?，我错了。我如何设置这些方法有问题吗？它们看起来非常简单，所以我不明白为什么没有返回 true 以供记录。

控制台输出：

user = User.last
#<User id: 18, first_name: "gjalrgkj", last_name: "kgjrlgakjrl", email: "terajglrkj@gmail.com", password_digest: "a$WF.Rw3PzlWilH0X.Nbfxfe5aB18WW6J7Rt4SAKQEwI8...", remember_digest: nil, activation_digest: "a$/bXG4/nKCiiZHWailUPAmOZj7YhCjKhPm4lUW6nPC3N...", activated: nil, activated_at: nil, reset_digest: nil, reset_sent_at: nil, account_type: "Student", created_at: "2018-07-02 04:21:07", updated_at: "2018-07-02 04:21:07">
>> user.account_type
=> "Student"
>> user.account_type = "Student"
=> "Student"
>> user.student?
=> false

用户模型：

class User < ApplicationRecord
  has_one :personal_information

  attr_accessor :remember_token, :activation_token, :reset_token
  before_save   :downcase_email
  before_create :create_activation_digest
  validates :first_name,  presence: true, length: { maximum: 50 }
  validates :last_name,  presence: true, length: { maximum: 50 }
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-]+(\.[a-z\d\-]+)*\.[a-z]+\z/i
  validates :email, presence: true, length: { maximum: 255 },
                      format: { with: VALID_EMAIL_REGEX },
                      uniqueness: { case_sensitive: false }
  has_secure_password
  validates :password, presence: true, length: { minimum: 6 }, allow_nil: true
  validates :account_type, presence: true


  def User.new_token
    SecureRandom.urlsafe_base64
  end

  def User.digest(string)
    cost = ActiveModel::SecurePassword.min_cost  BCrypt::Engine::MIN_COST :
                                              BCrypt::Engine.cost
    BCrypt::Password.create(string, cost: cost)
  end

  def create_reset_digest   
    self.reset_token = User.new_token
    update_columns(reset_digest: User.digest(reset_token), reset_sent_at: Time.zone.now)
  end

  def authenticated?(attribute, token)
    return false if digest.nil?
 BCrypt::Password.new(digest).is_password?(token)
  end


  def remember
    self.remember_token = User.new_token
    update_attribute(:remember_digest, User.digest(remember_token))
  end

  def forget
    update_attribute(:remember_digest, nil)
  end


  def provide_age
    now = Time.now.utc.to_date
    if self.birthday.nil?
      nil
    else
      self.age = now.year - self.birthday.year - ((now.month > self.birthday.month || (now.month == self.birthday.month && now.day >= self.birthday.day)) ? 0 : 1)
      update_attribute(:age, self.age)
    end
  end


  def send_activation_email
    UserMailer.account_activation(self).deliver_now
  end  

  def activate
    update_columns(activated: true, activated_at: Time.zone.now)
  end

  def send_password_reset_email
    UserMailer.password_reset(self).deliver_now
  end

  def password_reset_expired?
    reset_sent_at < 2.hours.ago
  end


  private 

  def downcase_email
    self.email.downcase!
  end

  def create_activation_digest
    self.activation_token  = User.new_token
    self.activation_digest = User.digest(activation_token)
  end
end

用户助手

  def account_type
    [
      ['Student'], 
      ['Partner'], 
      ['School Administrator'], 
      ['Philanthropist']
    ]
  end

  def student?
    self.account_type == "Student"
  end

  def partner?
    self.account_type == "Partner"
  end
 end

Answer 1

您的 2 个方法 student? 和 partner? 属于用户模型。

当您执行 user.student? 时，它会在用户模型中查找 student? 方法作为实例方法。

self 中的 helper 不是它指向你的 helper 模块的用户实例。

希望这对您有所帮助。

Answer 2

尝试将此代码放入您的用户模型（而不是助手）

def student?
  self.account_type == "Student"
end

def partner?
  self.account_type == "Partner"
end

创建一个 setter 来设置 account_type 是个好主意，例如

def set_account_type(type)
  self.account_type = type
end

你能帮我理解为什么这个布尔方法返回 false 吗？

Can you help me understand why this boolean method is returning false?

ruby-on-rails

boolean-expression