复杂范围，Rails 3答案

【问题标题】：Complex Scope, Rails 3复杂范围，Rails 3
【发布时间】：2011-11-05 06:34:42
【问题描述】：

所以我正在构建一个匹配用户的应用程序。用户模型有 3 个属性（无论如何都与我的问题相关：gender:string、looking_for_men:boolean、looking_for_women:boolean。

目前我的模型中有这样的方法：

def browse
  if self.looking_for_men == true && self.looking_for_women == true
    if self.sex == "Male"
      User.where("looking_for_men = ?", true)
    elsif self.sex == "Female"
      User.where("looking_for_women = ?", true)
    end
  elsif self.sex == "Male" && self.looking_for_men == true
    User.where("looking_for_men = ? AND sex = ?", true, "Male")
  elsif self.sex == "Female" && self.looking_for_women == true
    User.where("looking_for_women = ? AND sex = ?", true, "Female")
  else
    if self.sex == "Male"
      User.where("looking_for_men = ? AND sex = ?", true, "Female")
    elsif self.sex == "Female"
      User.where("looking_for_women = ? AND sex = ?", true, "Male")
    end
  end
end

如您所知，这非常混乱。无论如何要清理它并使其成为一个范围，例如我是一个男性用户，我正在寻找女性，当我进行这样的查询时它只返回正在寻找男性的女性：

@users = User.all.browse

【问题讨论】：

标签： ruby-on-rails ruby-on-rails-3 activerecord scope

【解决方案1】：

我会做下面的代码，使其更具可读性。但不知何故，我对这个解决方案并不完全满意。还是很多代码：

class User < ActiveRecord::Base
  scope :male,   where(:gender => "Male")
  scope :female, where(:gender => "Female")
  scope :looking_for_men,   where(:looking_for_men => true)
  scope :looking_for_women, where(:looking_for_women => true)

  def browse
    @women = @men = []

    @women = self.interested_females if self.looking_for_women
    @men   = self.interested_males   if self.looking_for_men

    @result = @women.concat(@men)
    @result.delete(self) #removes the user itself from the result-set

    return @result
  end

  def interested_females
    return User.female.looking_for_men   if self.male?
    return User.female.looking_for_women if self.female?
  end

  def interested_males
    return User.male.looking_for_men   if self.male?
    return User.male.looking_for_women if self.female?
  end

  def male?
    return (self.gender == "Male")
  end

  def female?
    return (self.gender == "Female")
  end
end

【讨论】：

我喜欢这个。我将重命名范围 looking_for_men 和 looking_for_women 只是为了便于阅读（与布尔值冲突）；但这并不是真正需要的。

【解决方案2】：

仅从作用域的角度来看，只需将逻辑传递给 proc，您就可以相当容易地将逻辑移到作用域中。

class User
  scope :browse_for, lambda { |user|
      user.looking_for_men == true && user.looking_for_women == true
      ...
  }
end

@users = User.browse_for(@single_male)

您还可以将范围链接在一起以清理逻辑：http://edgerails.info/articles/what-s-new-in-edge-rails/2010/02/23/the-skinny-on-scopes-formerly-named-scope/index.html。

我不确定这是否完全回答了你的问题？

【讨论】：