Question

我的数据库架构：

tournaments(id, ...)
teams(tournament_id, id, ...)
matches(tournament_id, id, team_id_home, team_id_away, ...)

型号：

class Tournament < ActiveRecord::Base
    has_many :teams, dependent: :destroy
    has_many :matches, dependent: :destroy
    ...
end

class Team < ActiveRecord::Base
    belongs_to :tournament
    ...
end

class Match < ActiveRecord::Base
    belongs_to :tournament
    has_many :teams
    ...
end

我希望在我看来有以下数据：

match_id  team_id_home  team_id_away  team_id_home_name  team_id_away_name

所以，我正在寻求以下查询的帮助（我正在尝试获取团队名称，但是加入时遇到问题）：

@matches = @tournament.matches.where(:tournament => @tournament).joins(:teams).paginate(page: params[:page])

Answer 1

我对rails很新，但你应该能够设置你的关联:(从内存中去）

class Match < ActiveRecord::Base
    belongs_to :tournament
    has_one :home_team, :class_name => "Team", :foreign_key => "team_id_home"
    has_one :away_team, :class_name => "Team", :foreign_key => "team_id_away"
end

#####

m = Match.first
m.away_team.team_name
m.home_tam.team_name

或者在你的情况下：

@matches = @tournament.matches.paginate(page: params[:page])

我认为你不需要where函数：has_many关联告诉rails只能匹配匹配。

Answer 2

匹配模型中的belongs_to，而不是has_one。

class Match < ActiveRecord::Base
    belongs_to :tournament
    belongs_to :home_team, :class_name => "Team", :foreign_key => "team_id_home"
    belongs_to :away_team, :class_name => "Team", :foreign_key => "team_id_away"
end

class Team < ActiveRecord::Base
    belongs_to :tournament
    has_many :matches
end

现在我可以在我的视图中使用tournament.home_team.name

加入一张桌子两次

2 个答案: