在Rails中使用多态模型连接数据库视图 [英] Connecting database view with polymorphic model in rails

问题描述

我具有以下设置，该设置允许用户拥有多个项目，并且每个项目可以具有多个任务.用户可以收藏多个项目.

I have the following setup which allows a user to have multiple projects and each project can have multiple tasks. A user can favourite multiple projects.

class User < ActiveRecord::Base
  has_many :projects
  has_many :tasks, :through => :projects
  has_many :favourites
  has_many :favourite_projects, :through =>  :favourites, :source => :favourable, :source_type => "Project"
  has_many :favourite_tasks, :through => :favourite_projects, :source => :tasks
  ...
end

class Project < ActiveRecord::Base
  belongs_to :user
  has_many :tasks
  has_many :favourites, :as => :favourable
  ...
end

class Task < ActiveRecord::Base
  belongs_to :project
  ...
end

class Favourite < ActiveRecord::Base
  belongs_to :user
  belongs_to :favourable, :polymorphic => true
  ...
end

此设置允许@user.favourite_tasks列出他们喜欢的项目的所有任务.

This setup allows @user.favourite_tasks to list all the tasks for the projects that they have favourited.

从这里接受建议( http://pivotallabs.com/database-views-performance -rails/)我正在尝试尽可能用数据库视图替换多级表联接.

Taking the suggestion from here (http://pivotallabs.com/database-views-performance-rails/) I am trying to replace the multi-level table joins with a database view where possible instead.

视图SQL是:

SELECT tasks.id AS task_id, ..., projects.id AS project_id, ... 
FROM tasks INNER JOIN projects ON projects.id = tasks.project_id

我的新ProjectTask模型是:

class ProjectTask < ActiveRecord::Base
  self.primary_key = 'task_id'
end

我已经更新了我的User模型，使其包括:

I've updated my User model to include:

has_many :project_tasks

对@user.project_tasks正常.

但是，我无法弄清楚模型中的has_many/has_one/belongs_to应该是什么，以便收藏夹可以工作(将收藏夹连接到视图而不是项目表).

However, I can't figure out what the has_many/has_one/belongs_to should be in the models for the favourites to work (connecting the favourites to the view rather than the projects table).

我的目标是has _many :favourite_project_tasks, :through => :favourites....，以便可以在控制器中使用@user.favourite_project_tasks并在需要时将任何ProjectTask模型范围附加到该范围. 我认为ProjectTask模型具有task_id作为主键的事实正在导致链接表/视图的轨道问题，并且因为使用:through会覆盖对:foreign_key和:primary_key的任何使用(根据 http://apidock.com/rails/ActiveRecord/Associations/ClassMethods/has_many ).

I'm aiming for has _many :favourite_project_tasks, :through => :favourites.... so that I can use @user.favourite_project_tasks in my controller and attach any ProjectTask model scopes to it if need be. I think the fact that the ProjectTask model has task_id as the primary key is causing issue with rails linking the tables/view and because using :through overrides any use of :foreign_key and :primary_key (according to http://apidock.com/rails/ActiveRecord/Associations/ClassMethods/has_many).

希望有人可以建议我应该做些什么，因为我已经尝试了很多变化的组合，但并不高兴.

Hopefully someone can advise what I should be doing because I've tried loads of combinations of changes with no joy.

谢谢

推荐答案

问题似乎是由自定义主键引起的.

Issue seems to have been caused by the custom primary key.

通过使用User模型更新(失败时我已经在执行此操作):

By updating the User model with (I was already doing this when it was failing):

has_many :favourite_project_tasks, :through => :favourite_projects, :source => :project_tasks

使用视图，也将视图更改为使用:

to use the view and also changing the view to use:

SELECT tasks.id AS id, ...

而不是:

SELECT tasks.id AS task_id, ...

，并更改ProjectTask视图模型以使用:

and changing the ProjectTask view model to use:

self.primary_key = :id

现在可以使用.

这篇关于在Rails中使用多态模型连接数据库视图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！