ruby-on-rails - Rails 如果存在则更新，否则使用 find_or_create_by 创建

Question

我正在尝试运行一种方法，如果存在(表 Hashtag 列标签)标记，它会将 View 计数更新为 1。否则它将创建一个新行，默认 View 计数为 0 并且标记为 @hashtag scrubbed .

Hashlog.rb

def self.create_hashlog(hashtag)        #enters hashtag into the log table, without #. 
        @hashtag_scrubbed = hashtag
        # Hashlog.find_or_create_by_tag(@hashtag_scrubbed) 

        taglog = Hashlog.find_or_create_by_tag(@hashtag_scrubbed) do |t|
        t.count = 0
        end
        taglog.count += 1
        taglog.save!    
    end

错误

Completed 500 Internal Server Error in 772ms

NoMethodError (undefined method `+' for nil:NilClass):
  app/models/hashlog.rb:24:in `create_hashlog'
  app/controllers/hashtags_controller.rb:32:in `create'

Answer 1

如果您的查找失败(因为没有记录)并且您的创建失败(因为验证失败)，该函数返回 nil。