如何将此 find_by_sql 转换为 named_scope？答案

【问题标题】：How transform this find_by_sql to named_scope?如何将此 find_by_sql 转换为 named_scope？
【发布时间】：2010-05-25 22:28:58
【问题描述】：

我怎么可能变成named_scope？

def self.hero_badge_awardees
        return User.find_by_sql("select users.*, awards.*, badges.badge_type 
          from users, awards, badges 
          where awards.user_id = users.id and badges.id = awards.badge_id and badges.badge_type = 'HeroBadge'")
      end

【问题讨论】：

标签： sql ruby-on-rails named-scope

【解决方案1】：

class Badge
  has_many :awards
end

class Award
  belongs_to :badge
  belongs_to :user
end

class User
 has_many :awards
 has_many :badges, :through => :awards
 named_scope :with_badge,
   lambda { |badge_type|
     :include => :badges,
     :conditions => ["badges.badge_type = ?", badge_type]
   }
end

那你可以试试：

User.with_badge("HeroBadge")

这看起来应该对我有用，但我还没有测试过。不过，希望这能给您带来启发。

【讨论】：

不。得到以下错误：语法错误，意外 tASSOC，期待 '}'

【解决方案2】：

要具体回答您的问题，请尝试以下操作：

class Badge
  has_many :awards
end

class Award
  belongs_to :badge
  belongs_to :user
end

class User
  has_many :awards
  has_many :badges, :through => :awards

  named_scope :hero_badge_awardees,
    :include => [:awards, :badges],
    :conditions => "badges.badge_type = 'HeroBadge'"
end

【讨论】：