如何更新 RoR 模型的关联而不更新相应模型的属性

Question

我的 Rails 3 应用程序中有以下模型（带有相应的数据库表）：

class User < ActiveRecord::Base
  has_many :service_users
  has_many :services, :through => :service_users

  attr_accessor :password

  attr_accessible :password, :password_confirmation, :service_ids

  validates :password, :presence => true,
                       :confirmation => true,
                       :length => { :within => 6..40 }
  ...
end

class Service < ActiveRecord::Base
  has_many :service_users
  has_many :users, :through => :service_users
  ...
end


class ServiceUser < ActiveRecord::Base
  belongs_to :service
  belongs_to :user
end

#User Controller:

class UsersController < ApplicationController
  ...
  def update
    @user = User.find(params[:id])
    if @user.update_attributes(params[:user])
      flash[:success] = "Profile updated."
      redirect_to @user
    else
      @title = "Edit user"
      render 'edit'
    end
  end
  ...
end

我希望能够更新用户模型的关联服务，而不必指定密码和密码确认属性。我该怎么做？

Answer 1

两个选项...

如果您有简单的逻辑，例如仅在创建用户时验证密码，这将起作用：

validates :password, :presence => true,
                     :confirmation => true,
                     :length => { :within => 6..40 },
                     :if => :new_record?

更有可能的是，您需要一个组合，以便用户可以更新其密码：

validates :password, :presence => true,
                     :confirmation => true,
                     :length => { :within => 6..40 },
                     :if => :is_password_validation_needed?

# Protect the password attribute from writing an
# empty or nil value
def password=(pass)
  return if !pass.present?
  @password = pass
end

private 

  def is_password_validation_needed?
    # Return true if the record is unsaved or there
    # is a non-nil value in self.password
    new_record? || password
  end

Answer 2

这可能会有所帮助：

http://railscasts.com/episodes/41-conditional-validations

Answer 3

您将需要研究条件验证，以指定在更新/保存模型时是否应验证模型中的密码属性。这是一个 Railscast 剧集，虽然有点过时，但仍然相当简单，应该得到你走在正确的道路上