HABTM重复记录 [英] HABTM duplicate records

问题描述

我有2个型号Game& Theme，并且它们具有has_and_belongs_to_many关联.我尝试了许多解决方案来防止games_themes表中的重复记录，但是没有解决方案.问题是games_themes是一个表，但不是模型，因此我无法找到一种有效地对其进行验证的方法.

I have a 2 models Game & Theme and they have a has_and_belongs_to_many association. I have tried many solutions to prevent duplicate records in the games_themes table, but no solutions work. The problem is, games_themes is a table, but it is not a model, so I can't figure out a way to run validations on it effectively.

这里有我尝试过的解决方案

Heres a solution I tried

class Theme < ActiveRecord::Base
  has_and_belongs_to_many :games, :uniq => true
end

class Game < ActiveRecord::Base
  has_and_belongs_to_many :themes, :uniq => true
end

推荐答案

您应使用数据库级验证:

You should use database-level validation:

#new_migration
add_index :games_themes, [:game_id, :theme_id], :unique => true

---

HABTM

这将防止您在数据库中保存任何重复的数据.减轻Rails&确保您只有游戏或主题.问题是因为HABTM没有模型，您无法在Rails中执行验证，这意味着您需要使其成为数据库级别

This will prevent you saving any duplicate data in the database. Takes the burden off Rails & ensures you only have game or theme. The problem is because HABTM doesn't have a model, there's no validation you can perform in Rails, meaning you need to make it db-level

如评论中所述，这意味着您必须像这样处理从数据库引发的异常:

As mentioned in the comments, this means you'll have to handle the exceptions raised from the db like this:

#app/controllers/games_controller.rb
def create
    #creation stuff here
    if @game.save
        #successful save
    else
        #capture errors
    end
end

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