ruby-on-rails - 如何解决 'column identifier is not unique' ？

Question

我正在根据过时的指南构建 url 缩短器，这意味着需要进行大量调试。我第一次运行缩短器时，它起作用了。

现在，在提交链接时，它会返回此错误:“列标识符不是唯一的”

 private 
      def self.create_link(original)
        url = Url.create(:original => original)
        if Link.first(:identifier => url.id.to_i.to_s(36)).nil? or !DIRTY_WORDS.include? url.id.to_i.to_s(36)
          link = Link.new(:identifier => url.id.to_i.to_s(36))
          link.url = url
          link.save
          return link
        else 
          create_link(original)
        end
      end
    end 

错误指的是这一行。

link.save

在此先感谢您的帮助!

这些是模型。

class Url
  include DataMapper::Resource 
  property  :id,        Serial
  property  :original,  String, :length => 255
  belongs_to    :link
end



class Link 
  include DataMapper::Resource 
  property :identifier, String, :key => true
  property :created_at, DateTime
  has 1, :url 
  has n, :visits

  def self.shorten(original, custom=nil)
    url = Url.first(:original => original)
    return url.link if url
    link = nil
    if custom
      raise 'Someone has already taken this custom URL, sorry' unless 
  Link.first(:identifier => custom).nil?
      raise 'This custom URL is not allowed because of profanity' if 
  DIRTY_WORDS.include? custom
      transaction do |txn|
        link = Link.new(:identifier => custom)
        link.url = Url.create(:original => original)
        link.save
      end
    else 
      transaction do |txn|
        link = create_link(original)
      end
    end 
    return link 
  end 

  private 
  def self.create_link(original)
    url = Url.create(:original => original)
    if Link.first(:identifier => url.id.to_i.to_s(36)).nil? or !DIRTY_WORDS.include? url.id.to_i.to_s(36)
      link = Link.new(:identifier => url.id.to_i.to_s(36))
      link.url = url
      link.save
      return link
    else 
      create_link(original)
    end
  end
end 


class Visit
  include DataMapper::Resource

  property  :id,            Serial
  property  :created_at,    DateTime
  property  :ip,            IPAddress
  property  :country,       String
  belongs_to    :link

  after :create, :set_country

  def set_country
    xml = RestClient.get "http://api.hostip.info/get_xml.php?ip=#{ip}"
    self.country = XmlSimple.xml_in(xml.to_s, { 'ForceArray' => false})['featureMember']['Hostip']['countryAbbrev']
    self.save
  end

  def self.count_days_bar(identifier,num_of_days)
    visits = count_by_date_with(identifier, num_of_days)
    data, labels = [], []
    visits.each {|visit| data << visit[1]; labels << "#{visit[0].day}/#{visit[0].month}" }
    "http://chart.apis.google.com/chart?chs=820x180&cht=bvs&chxt=x&chco=a4b3f4&chm=N,000000,0,-1,11&chxl=0:|#{labels.join('|')}&chds=0,#{data.sort.last+10}&chd=t:#{data.join(',')}"
  end

  def self.count_country_chart(identifier,map)
    countries, count = [], []
    count_by_country_with(identifier).each {|visit| countries << visit.country; count << visit.count}
    chart = {}
    chart[:map] = "http://chart.apis.google.com/chart?chs=440x220&cht=t&chtm=#{map}&chco=FFFFFF,a4b3f4,0000FF&chld=#{countries.join('')}&chd=t:#{count.join(',')}"
    chart[:bar] = "http://chart.apis.google.com/chart?chs=320x240&cht=bhs&chco=a4b3f4&chm=N,000000,0,-1,11&chbh=a&chd=t:#{count.join(',')}&chxt=x,y&chxl=1:|#{countries.reverse.join('|')}"
    return chart
  end 

  def self.count_by_date_with(identifier,num_of_days)
    visits = repository(:default).adapter.query("SELECT date(created_at) as date, count(*) as count FROM visits where link_ = '#{identifier}' and created_at between CURRENT_DATE-#{num_of_days} and CURRENT_DATE+1 group by date(created_at)")
    dates = (Date.today-num_of_days..Date.today)
    results = {}
    dates.each { |date|
      visits.each { |visit| results[date] = visit.count if visit.date == date }
      results[date] = 0 unless results[date]
    }
    results.sort.reverse 
  end 

  def self.count_by_country_with(identifier)
    respository(:default).adapter.query("SELECT country, count(*) as count FROM visits where link_identifier = '#{identifier}' group by country")
  end
end 

Answer 1

好吧，直到更有知识的人插话...... 我不知道 Ruby 或 Ruby on Rails，但我知道数据库，这听起来完全像是主键验证错误。我怀疑您的 link.id 字段需要是唯一的，并且第二次运行该程序时它会生成相同的 ID。您很有可能需要创建一个唯一的 ID，或者放宽对 ID 字段的限制以允许重复(当您通过 ID 检索内容时，这可能会导致问题)。