ruby-on-rails - Rails 中的两列不能彼此相等

Question

我正在 Rails 中创建一个社交网络，我有一个这样的模型:

create_table "friendships", :force => true do |t|
    t.integer  "user1_id"
    t.integer  "user2_id"
    t.boolean  "hasaccepted"
    t.datetime "created_at"
    t.datetime "updated_at"
end

问题是你不能将自己添加为 friend ，所以我在我的模型中尝试了这个:

def validate
    if :user1_id == :user2_id
        record.errors.add "You cannot add yourself as a friend."
        return false
    end
end

我的 Controller 中有这个:

def addfriend
    if params[:id]
        @friendship = Friendship.new()
        @friendship.user1_id = session[:user]
        @friendship.user2_id = params[:id]
        respond_to do |format|
            if @friendship.save
                format.html { redirect_to "/" } # Yes, SO users, I will fix this redirect later and it is not important for now.
                format.xml  { render :xml => @friendship, :status => :created }
            else
                format.html { redirect_to "/" }
                format.xml  { render :xml => @friendship.errors, :status => :unprocessable_entity }
            end
        end
    end
end

(其中 session[:user] 是当前登录用户的 uid)

然而，当我去 http://localhost:3000/profile/addfriend/2.xml当我以用户身份登录时 2 , Rails 还给我新的 Friendship ，而不是错误消息，当我查看我的数据库时， Friendship也在那里(它不应该)。有人可以解释我如何解决这个问题吗？谢谢

Answer 1

像这样尝试:

class Friendship < ActiveRecord::Base
  validate :cannot_add_self

  private

  def cannot_add_self
    errors.add(:user2_id, 'You cannot add yourself as a friend.') if user1_id == user2_id
  end
end