Question

我有以下型号

class Player < ActiveRecord::Base
  has_many :players_to_teams
  has_many :teams, through: :players_to_teams
end

class Team < ActiveRecord::Base
  has_many :players_to_teams
  has_many :players, through: :players_to_teams
  belongs_to :account
end

这些是通过players_to_teams表加入的：

class PlayersToTeam < ActiveRecord::Base
  belongs_to :player
  belongs_to :team
end

players_to_teams有一个名为BT的列。我无法访问此专栏。

这失败了：

player = Player.find(13)
player.players_to_teams.BT

出现此错误：

NoMethodError:   undefined method `BT' for #<ActiveRecord::Relation:0x007fd52f170c58>
PlayersToTeam Load (332.2ms)    from /Users/Tyler/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/relation/delegation.rb:45:in `method_missing'
  SELECT `players_to_teams`.* FROM `players_to_teams` WHERE `players_to_teams`.`player_id` = 13
    from /Users/Tyler/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/associations/collection_proxy.rb:101:in `method_missing'
    from (irb):4
    from /Users/Tyler/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/commands/console.rb:47:in `start'
    from /Users/Tyler/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in `start'
    from /Users/Tyler/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/commands.rb:41:in `<top (required)>'
    from /Users/Tyler/Development/Rails/csbb/script/rails:6:in `require'
    from /Users/Tyler/Development/Rails/csbb/script/rails:6:in `<top (required)>'
    from -e:1:in `load'
    from -e:1:in `<main>'

但是，这可以工作：

player.players_to_teams.select("BT")

有没有办法在不使用select选项的情况下访问Rails 3.2.1中连接表中存储的值？

由于

Answer 1

由于players_to_teams是一个连接表而你还没有运行它，你得到一个关系。

首先，您需要为集合调用all或首先调用单个PlayersToTeam对象。

另外，我非常肯定它会因为大写（因为Ruby中的常量有大写字符）而会阻塞一个名为BT的方法。

访问连接表轨道的列

1 个答案: