Ruby数据映射器不'；t商店不属于

我有两种DataMapper型号：

class Address
  include DataMapper::Resource

  property :id, Serial
  property :url, String, :required => true

  has n, :logs
end

class Log
  include DataMapper::Resource

  property :id, Serial
  property :useragent, String

  belongs_to :address
end

我使用Sinatra创建新地址，并在另一种方法中记录属于这些地址的日志

  # page after posting a form
  post '/' do
    @messages = []

    if (params[:url] =~ URI::regexp).nil?
      @messages.push('URL is not valid!')
    else
      address = Address.create(:url => params[:url])

      base36 = address.id.to_s(36)
      @messages.push(request.url + base36)
    end

    erb :index
  end

  # redirection from a short url
  get '/:base36' do |base36| 
    # probably not necessary...
    if base36 =~ /[[:alnum:]]+/
      begin
        id = base36.to_i(36)
        address = Address.get(id)

        log = Log.create(:useragent => request.user_agent)
        address.logs << log
        # log.save
        address.save
        # address.logs.save

        address.logs.length.to_s
        # redirect address.url
      rescue
        redirect '/'
      end
    else
      redirect '/'
    end
  end

视图总是
0
。这个代码有什么问题


好的，所以我尝试将字符串字段推到过长的useragent。字符串限制为50个字符。#datamapper irc频道的人帮了我的忙，
.save
方法在这种情况下返回false，数据不会被存储。
评论说：

address.logs << log
# log.save

将日志推送到日志集后保存日志：

log = Log.new(:useragent => request.user_agent)
address.logs << log
log.save # not a comment, just a self-explaining code

log=log.new（：useragent=>request.user\u agent）
address.logsOK，所以我尝试将字符串字段推到过长的useragent。字符串限制为50个字符。#datamapper irc频道上的人帮了我的忙。在这种情况下，.save方法返回false，数据未存储

log = Log.create(:useragent => request.user_agent, :address => address)

log = Log.new(:useragent => request.user_agent)
address.logs << log
log.save # not a comment, just a self-explaining code