Question

我知道,“归属者:通过”是不有效的。我只是试图表达我想要实现的目标。同我一样,我sec......

这是我拥有的:

class League
  has_many :divisions
end

class Division
  belongs_to :league
  has_many :teams
end

class Team
  belongs_to :division
  has_many :players
end

class Player
  belongs_to :team
end

Now, in order to make a "baseball card" view form, I need:

name
team.name
team.division.name
team.division.league.name

因此,现在可以建立“归属者:通过”协会直接进入司。角色名称: 没有小组的控制人员。预先确定? 我不得不从参与者到司处打一栏,这样我就想设法“直接”进入这些栏目。

One option is to include a division_id column in the players table, but I ve been told that it would kinda break the relational data model, since it would allow for inconsistency if the data selection functionality is not properly handled (e.g. player A is on team A which is in division A, but player A has its division_id column set to division B).

是否有可能建立“代谢联系”,例如现在司指的是团队。司和ague现在指的是小组。

或者,每次使用全部道路的唯一真正选择吗?

希望的人能够提供帮助。

Answer 1

示范类别中的使用代表。

class Team < ActiveRecord::Base
  belongs_to :division
  has_many :players

  delegate :league, to: :division
end

参考:

Answer 2

You may try

    class Player
      belongs_to :team
      has_one :division, :through => :team
    end

Answer 3

你们可以界定你的角色模式中的帮助方法:

def division
  team.division
end

def league
  team.division.league
end

Of course, this only relates to readability of your code and does not affect the form of the database queries involved. If your statement generates multiple SQL queries but you want only one, check out the .include option here: Rails Guides - Active Record Query Interface

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