belongs_to的HAS_ONE结构 [英] belongs_to has_one structure

问题描述

我有具有以下特征的应用程序

 有俱乐部
每个俱乐部都有团队
每支球队都有球员
 

我有一个用户表。用户表基本上包含用户名和密码为俱乐部经理，团队经理和玩家登录到系统中。

我应该如何结构化模型和表格？

我打算创建表的俱乐部，球队和球员。但我不知道展会上构建他们和用户表之间的关系。

我可以在每个模型的创建 USER_ID ，但这种关系是俱乐部belongs_to的用户这没有按'牛逼似乎是正确的。而且我会最终有一个用户模式，具有以下

  HAS_ONE：俱乐部
HAS_ONE：团队
HAS_ONE：球员
 

这是不正确的。的用户将其中只有一个在任何给定的时间。

有没有更好的方式来组织呢？

解决方案

在Rails中， HAS_ONE 真的最多有一个。这是完全有效的有三个 HAS_ONE 装饰在用户。如果你想确保他们只有precisely之一，你可以添加一个验证，例如：

 类用户的LT;的ActiveRecord :: Base的
  HAS_ONE：俱乐部
  HAS_ONE：团队
  HAS_ONE：球员

  验证：has_only_one

  私人

  高清has_only_one
    如果[俱乐部，球队，球员] .compact.length！= 1
      errors.add_to_base（必须有$ P $的俱乐部，球队或球员pcisely 1）
    结束
  结束
结束
 

既然你已经更改数据库中的用户表的能力，我想我会放在 club_id ， TEAM_ID ， player_id 在用户，并具备以下条件：

 类俱乐部LT;的ActiveRecord :: Base的
  HAS_ONE：用户
  的has_many：团队
  的has_many：玩家：通过=＆GT; ：团队
结束

一流的团队及LT;的ActiveRecord :: Base的
  HAS_ONE：用户
  belongs_to的：俱乐部
  的has_many：玩家
结束

一流的球员和LT;的ActiveRecord :: Base的
  HAS_ONE：用户
  belongs_to的：团队
  HAS_ONE：俱乐部：通过=＆GT; ：球队
结束

类用户的LT;的ActiveRecord :: Base的
  belongs_to的：俱乐部
  belongs_to的：团队
  belongs_to的：播放器

  验证：belongs_to_only_one

  高清belongs_to_only_one
    如果[俱乐部，球队，球员] .compact.length！= 1
      errors.add_to_base（必须属于$ P $的俱乐部，球队或球员pcisely 1）
    结束
  结束
结束
 

我甚至想要重命名用户为管理​​，或者 HAS_ONE ：经理：将class_name =＆GT; 用户在俱乐部，团队和播放器的车型，但你的电话。

I have an application which has the following characteristics

There are Clubs
Each Club has Teams
Each Team has Players

I have a users table. The user table basically contains the username and password for the club manager, team manager and the player to login to the system.

How should I structure the models and the tables?

I plan to create tables for Club, Team and Players. But I am not sure show to structure the relationship between them and the users table.

I could create user_id in each of the model, but the relationship would be Club belongs_to User which doesn't seems right. Moreover I would end up with a User model that has the following

has_one :club
has_one :team
has_one :player

Which is not right. A user will have only one of them at any given time.

Is there a better way to structure this?

解决方案

Under Rails, has_one is really "has at most one". It's perfectly valid to have all three has_one decorators in User. If you want to ensure they only have precisely one, you could add a validation, for instance:

class User < ActiveRecord::Base
  has_one :club
  has_one :team
  has_one :player

  validate :has_only_one

  private

  def has_only_one
    if [club, team, player].compact.length != 1
      errors.add_to_base("Must have precisely one of club, team or player")
    end
  end
end

Since you have the ability to change the users table in the database, I think I would put club_id, team_id, player_id in users, and have the following:

class Club < ActiveRecord::Base
  has_one :user
  has_many :teams
  has_many :players, :through => :teams
end

class Team < ActiveRecord::Base
  has_one :user
  belongs_to :club
  has_many :players
end

class Player < ActiveRecord::Base
  has_one :user
  belongs_to :team
  has_one :club, :through => :team
end

class User < ActiveRecord::Base
  belongs_to :club
  belongs_to :team
  belongs_to :player

  validate :belongs_to_only_one

  def belongs_to_only_one
    if [club, team, player].compact.length != 1
      errors.add_to_base("Must belong to precisely one of club, team or player")
    end
  end
end

I'd even be tempted to rename User as Manager, or have has_one :manager, :class_name => "User" in the Club, Team and Player models, but your call.

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