Question

我有以下型号

class User < ActiveRecord::Base
  has_many :occupations,     :dependent => :destroy
  has_many :submitted_jobs,  :class_name => 'Job', :foreign_key => 'customer_id'
  has_many :assigned_jobs,   :class_name => 'Job', :foreign_key => 'employee_id'
end

class Job < ActiveRecord::Base
  belongs_to :customer, :class_name => 'User', :foreign_key => 'customer_id'
  belongs_to :employee, :class_name => 'User', :foreign_key => 'employee_id'
  belongs_to :field
end

class Occupation < ActiveRecord::Base
  belongs_to :user
  belongs_to :field
  belongs_to :expertise
end

以及Field（只是名称和ID）和Expertise（名称和整数排名）。

我需要创建一个类似于以下伪代码的过滤器

select * from jobs where employee_id == current_user_id
or employee_id == 0
  and current_user has occupation where occupation.field == job.field
  and if job.customer has occupation where occupation.field == job.field
    current_user.occupations must include an occupation where field == job.field
      and expertise.rank > job.customer.occupation.expertise.rank

你可以通过这个复杂的查询看到我如何快速耗尽我的SQL知识。

你会怎么做？正确的SQL会很棒，但如果一个Rails人员可以指出我使用ActiveRecord方法的正确方法，那也很棒。或许我不是很好地构建我的模型;我愿意接受各种建议。

谢谢！

Answer 1

我可能错过了一些内容，并没有考虑重构模型，但是可能有助于您获得完整解决方案或如何重新构建查询的内容

未对代码进行测试或语法检查

@jobs = Job.
    joins(:employee,:occupation).
    includes(:customer => {:occupations => :expertise}).
    where(:employee_id => current_user.id).
    where("occupations.field_id = jobs.field_id").all

user_occupations = current_user.occupations.include(:expertise)

user_occupations_by_field_id = user_occupations.inject({}) do |hash,oc|
    hash[oc.field_id] = oc
    hash
end

@jobs.reject! do |j|
  common_occupations = j.customer.occupations.select do |oc|
    if c = user_occupations_by_field_id[oc.field_id]
        !user_occupations.select do |eoc|
            c.field_id == eoc.field_id && c.expertise.rank > oc.expertise.rank
        end.empty?
    else
        true
    end
  end

end

帮助处理具有太多连接的复杂ActiveRecord查询

1 个答案: