将记录添加到has_and_belongs_to_many关系

问题描述

我有两种模式，用户和促销.这个想法是，促销可以有很多用户，而一个用户可以有很多促销.

I have two models, users and promotions. The idea is that a promotion can have many users, and a user can have many promotions.

class User < ActiveRecord::Base
  has_and_belongs_to_many :promotions
end

class Promotion < ActiveRecord::Base
  has_and_belongs_to_many :users
end

我也有一个Promotions_users表/模型，没有自己的ID.它引用了user_id和Promotions_id

I also have a promotions_users table/model, with no id of its own. It references user_id and promotions_id

class PromotionsUsers < ActiveRecord::Base
end

那么，如何将用户添加到促销中?我已经尝试过这样的事情:

So, how do I add a user to a promotion? I've tried something like this:

user = User.find(params[:id])
promotion = Promotion.find(params[:promo_id])
promo = user.promotions.new(promo)

这将导致以下错误:

NoMethodError: undefined method `stringify_keys!' for #<Promotion:0x10514d420>

如果我改用这一行:promo = user.promotions.new(promo.id)

If I try this line instead:promo= user.promotions.new(promo.id)

我收到此错误:

TypeError: can't dup Fixnum

我确信对我的问题有一个非常简单的解决方案，而我只是没有以正确的方式寻找解决方案.

I'm sure that there is a very easy solution to my problem, and I'm just not searching for the solution the right way.

推荐答案

user = User.find(params[:id])
promotion = Promotion.find(params[:promo_id])
user.promotions << promotion

user.promotions是与用户相关联的促销的数组.

user.promotions is an array of the promotions tied to the user.

有关可用的所有不同功能，请参见 apidock .

See the apidock for all the different functions you have available.

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