对于＃<blogpost：0x0000000adb9110>，未定义的方法`last_comment_at ='

Question

我创建了新帖子：

    def create
    params[:blog_post][:draft] = params[:draft].present?
    @post = current_user.blog_posts.new(blog_post_params)
    @post.save!
    redirect_to @post, notice: (@post.draft? ? 'Черновик сохранен' : 'Пост опубликован')
  rescue ActiveRecord::RecordInvalid
    flash[:error] = ":("
    render :new
  end

当我创建新帖子时，显示错误：

undefined method `last_comment_at=' for #<BlogPost:0x0000000adb9110>


app/models/blog_post.rb:86:in `set_last_comment_at'
app/controllers/blog_posts_controller.rb:25:in `create'
config/initializers/flash_session_cookie_middleware.rb:19:in `call'

模型BlogPost：

class BlogPost < ActiveRecord::Base
  # attr_accessible :subject, :body, :tag_list, :commentable_by, :visible_by, :attachments_attributes
  include ActiveModel::ForbiddenAttributesProtection

  belongs_to :user
  has_many :comments, as: :owner, dependent: :destroy
  has_many :attachments, as: :owner, dependent: :destroy
  has_many :photos, through: :attachments, source: :asset, source_type: 'Photo'
  has_many :videos, through: :attachments, source: :asset, source_type: 'Video'
  belongs_to :article
  has_many :blog_post_subscriptions, dependent: :destroy
  has_many :subscribers, through: :blog_post_subscriptions, class_name: 'User', source: :user
  has_one  :poll, as: :owner, dependent: :destroy
  has_many :poll_items, dependent: :destroy

  accepts_nested_attributes_for :attachments, :allow_destroy => true
  accepts_nested_attributes_for :poll, allow_destroy: true,
                                    reject_if: proc { |attributes| attributes['question'].blank? }

  validates :user, :subject, :presence => true
  validates :body, presence: true, if: :body_required?
  validates :body, length: { maximum: 65000 }
  validate :validate_duplicate, on: :create

  def body_required?
    !article.present?
  end

  # after_create :bonus_for_blog_post
  # after_create :notify_subscribers
  before_create :check_paid_attributes
  after_create :set_last_comment_at

  def notify_subscribers!
    unless draft?
      Resque.enqueue BlogPostNotifier, self.id
    end
  end

  after_save :set_published_at

  def set_published_at
    if published_at.nil? and !draft?
      update_column :published_at, Time.now
      bonus_for_blog_post!
      notify_subscribers!
    end
  end

  define_index do
    indexes subject
    indexes body
    indexes tags_line
    indexes user.username, as: :blog_post_author

    has created_at
    has published_at
    where "draft=0"
    group_by 'subject, body, tags_line, blog_posts.published_at, users.username'

    set_property delta: ThinkingSphinx::Deltas::ResqueDelta
  end

  def to_s
    subject || "[без заголовка]"
  end

  scope :drafts, where(draft: true)
  scope :public, lambda { where(draft: false).where(:published_at.lte => Time.now) }
  scope :with_privacy, lambda { |u|
    unless u.moderator?
      friend_ids = u.friend_ids + [u.id]
      public.where(' blog_posts.visible_by IS NULL OR visible_by = "all" OR ' +
            '(blog_posts.visible_by = "me" AND user_id = ?) OR' +
            '(blog_posts.visible_by = "friends" AND user_id IN (?)) OR ' +
            '(blog_posts.visible_by = "fof" AND EXISTS ' +
            '(SELECT id FROM friendships WHERE friendships.user_id = blog_posts.user_id AND ' +
            'friendships.friend_id IN (?) LIMIT 1)) OR ' +
            '(blog_posts.visible_by = "bl" AND NOT EXISTS ' +
            '(SELECT id FROM black_list_items WHERE black_list_items.owner_type="User" AND black_list_items.owner_id=blog_posts.user_id AND black_list_items.blocked_user_id=?))', u.id, friend_ids, friend_ids, u.id)
    end
  }

  def set_last_comment_at
    self.last_comment_at = created_at
    save
  end

  acts_as_taggable
  scope :tagged, lambda {|tag| tagged_with(tag) if tag }
  before_save :set_tags_line
  def set_tags_line
    self.tags_line = tag_list.join(', ')
  end

  def user_can_edit?(user)
    self.user.id == user.id or user.moderator?
  end

  def user_can_comment?(u)
    u.can_comment_blog_post? self
  end

  protected

  def bonus_for_blog_post!
    unless draft?
      user.bonus(:blog_post_bonus)
    end
  end

  def check_paid_attributes
    unless user.paid?
      self.commentable_by = self.visible_by = 'all'
    end
  end

  def validate_duplicate
    errors.add(:base, :duplicate) unless user.blog_posts.where(body: body, article_id: article_id, :created_at.gt => 1.minute.ago).empty?
  end

  private

  after_update :expire_cache

  def expire_cache
    expire_fragment "#{dom_id}_body"
    expire_fragment "#{dom_id}_body_short"
    expire_fragment "#{dom_id}_attachments"
    Rails.cache.delete "#{dom_id}_tags"
  end

  before_save :emoji

  def emoji
    self.body = Rumoji.encode self.body
  end
end

我认为，问题在于：

 def set_last_comment_at
   self.last_comment_at = created_at
   save
 end

但为什么不能找到方法last_comment_at？

Answer 1

我修复了问题，我运行了迁移并将新列last_comment_at添加到表BlogPost