Rails的复杂关联

Question

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我想要的是获取所有未完成的项目，包括某个用户的所有未完成的任务。

到目前为止，这是我的设置：

User (devise)
    has_one :employee

Employee
    belongs_to :user
    has_and_belongs_to_many :tasks
    has_and_belongs_to_many :unfinished_tasks, :conditions => { :tasks => { :completed_at => nil } }, :class_name => "Task"
    has_many :unfinished_projects, :through => :unfinished_tasks, :source => :project, :uniq => true   ( :include => :unfinished_tasks OR :include => :tasks ? )

Project
    has_many :tasks

Task
    belongs_to :project
    has_and_belongs_to_many :employees

在我看来（haml）我想要这样的东西：

- for project in current_user.employee.unfinished_projects

    = project.name

    # THESE ARE NOT THE ONLY THE TASKS FOR THE CURRENT_USER
    - for task in project.tasks    ( OR project.unfinished_tasks ? )

        = task.name

此设置适用于项目，只有一些项目的任务尚未完成。

但是我不确定如何在这些项目中包括未完成的任务。

任何人都知道执行此操作的最佳方法，如果可能的话，我想对所有这些进行一个查询。

编辑：棘手的部分是任务必须为current_user。 项目已完美加载。

但是在加载任务时：

- for task in project.tasks.unfinished

它这样做：

Task Load (1.3ms)  SELECT `tasks`.* FROM `tasks` WHERE `tasks`.`project_id` IN (12, 7, 13, 15, 14, 10, 16, 17, 9, 2, 3)
Task Load (0.4ms)  SELECT `tasks`.* FROM `tasks` WHERE `tasks`.`project_id` = 12 AND `tasks`.`completed_at` IS NULL
Task Load (0.3ms)  SELECT `tasks`.* FROM `tasks` WHERE `tasks`.`project_id` = 7 AND `tasks`.`completed_at` IS NULL
Task Load (0.6ms)  SELECT `tasks`.* FROM `tasks` WHERE `tasks`.`project_id` = 13 AND `tasks`.`completed_at` IS NULL
etc.

它应该做的是获取员工的任务：

Employee
  Projects
    Tasks

哪些应该是项目查询中内部联接的任务。

Answer 1

假设我的问题（上面）是您想要看到的真实示例。

您可以使用named_scopes进行介绍。

例如：

Task
   named_scope :unfinished, :conditions => {:unfinished => true}

或用于表明未完成的任何条件。 然后，您可以使用：

 - for task in project.tasks.unfinished

“ unfinished_projects”的named_scope相似，但稍微复杂一些。 它需要一些裸露的SQL-这将取决于您使用的数据库，但是通常需要您加入任务并发现所完成的项目只有一项未完成的任务。 我猜测这可能接近您的需求：

Project
   named_scope :unfinished, 
    :joins => 'inner join tasks on tasks.project_id = projects.id',
    :conditions => ['tasks.unfinished IS TRUE']

然后，您将按上述方式使用它：

  - for project in current_user.employee.projects.unfinished

对于只为用户找到任务尚未完成的项目，可以将用户作为参数添加到范围中，例如：

Project
   named_scope :unfinished_for_user, lambda {|the_user_id|
    :joins => 'inner join tasks on tasks.project_id = projects.id',
    :conditions => ['tasks.unfinished IS TRUE AND tasks.user_id = ?', the_user_id]
   }

Answer 2

因此，我的问题的答案如下：

型号：

Employee:
  has_and_belongs_to_many :tasks
  has_many :projects, :through => :tasks, :uniq => true

Project:
  has_many :tasks
  scope :unfinished, :include => :tasks, :conditions => { :tasks => { :completed_at => nil } }

Task:
  scope :unfinished, :conditions => { :completed_at => nil }
  scope :of_user, lambda { |user| { :include => :employees, :conditions => { :employees => { :id => user.employee.id } } } }

风景：

- for project in current_user.employee.projects.unfinished

    - for task in project.tasks.unfinished.of_user( current_user )

我觉得非常烦人的是Project.unfinished已经包含了不完整的任务。

为什么我需要再次获取这些信息，所以给我每个项目的新查询！ 应该是不必要的吧？

Answer 3

因此，经过一遍又一遍的操作，我并没有真正发现问题所在。 现在有几处更改：我正在使用范围，包括用于急切加载的内容在范围内，而project.tasks本身没有范围。

项目模型：

has_many :tasks
scope :assigned_to, lambda { |employee| { :include => { :tasks => :employees }, :conditions => { :tasks => { :employees => { :id => employee.id } } } } }
scope :unfinished, :include => :tasks, :conditions => { :tasks => { :completed_at => nil } }

风景：

- for project in Project.assigned_to( current_user.employee ).unfinished
  = project.name
  - for task in project.tasks
    = task.name

给我这个不错的MySQL查询：

SELECT `projects`.`id` AS t0_r0, `projects`.`name` AS t0_r1, `projects`.`description` AS t0_r2, `projects`.`completed_at` AS t0_r3, `projects`.`created_at` AS t0_r4, `projects`.`updated_at` AS t0_r5, `tasks`.`id` AS t1_r0, `tasks`.`name` AS t1_r1, `tasks`.`description` AS t1_r2, `tasks`.`estimated_duration` AS t1_r3, `tasks`.`calculated_duration` AS t1_r4, `tasks`.`status` AS t1_r5, `tasks`.`completed_at` AS t1_r6, `tasks`.`project_id` AS t1_r7, `tasks`.`created_at` AS t1_r8, `tasks`.`updated_at` AS t1_r9, `employees`.`id` AS t2_r0, `employees`.`alias` AS t2_r1, `employees`.`comments` AS t2_r2, `employees`.`user_id` AS t2_r3, `employees`.`created_at` AS t2_r4, `employees`.`updated_at` AS t2_r5 FROM `projects` LEFT OUTER JOIN `tasks` ON `tasks`.`project_id` = `projects`.`id` LEFT OUTER JOIN `employees_tasks` ON `employees_tasks`.`task_id` = `tasks`.`id` LEFT OUTER JOIN `employees` ON `employees`.`id` = `employees_tasks`.`employee_id` WHERE `employees`.`id` = 3 AND `tasks`.`completed_at` IS NULL

奇迹般有效！

特别感谢Taryn ..;）