ruby-on-rails - 按belongs_to 自定义foreign_key 搜索

Question

我尝试通过两支球队搜索比赛，我尝试了几种语法，但没有任何帮助......

模型匹配：

class Match < ApplicationRecord
  belongs_to :home, class_name: 'Team', foreign_key: :home_id
  belongs_to :away, class_name: 'Team', foreign_key: :away_id
end

模特队：

class Team < ApplicationRecord
  has_many :home_matches, class_name: 'Match', foreign_key: :home_id
  has_many :away_matches, class_name: 'Match', foreign_key: :away_id

  # Fields: name
end

我试过这样的事情：

 Match.includes(:home, :away).where(homes: { name: 'Germany' }, aways: {name: 'China'})

错误：

ActiveRecord::StatementInvalid（PG::UndefinedTable: 错误：缺少表“homes”的 FROM 子句条目）

Answer 1

选项1。

在 Rails 控制台查询中检查puts Match.joins(:home, :away).to_sql。你可以得到如下结果：

SELECT "matches".* FROM "matches" INNER JOIN "teams" ON "teams"."id" = "matches"."home_id" INNER JOIN "teams" "away_matches" ON "away_matches"."id" = "matches"."away_id"

如果是这样，请使用查询

Match.joins(:home, :away).where(teams: { name: 'Germany' }, away_matches: {name: 'China'})

选项 2。

尝试查询

Match.where(home: Team.where(name: 'Germany'), away: Team.where(name: 'China'))

您还可以预先查找 Teams 的 ID：

home_id = Team.find_by(name: 'Germany').id
away_id = Team.find_by(name: 'China').id
Match.where(home_id: home_id, away_id: away_id)