Rails PG HABTM的关系

我有一个事实表，客户有很多业务：

bus_id, sales, date 1, $986, 1/1/2016 1, $543, 1/2/2016 2, $921, 1/1/2016 2, $345, 1/2/2016 

我想创造一个表机会

  bus_id, opportunity 1, "Upsell" 1, "Upsell More" 

如何创建两者之间具有has_and_belongs_to_many关系的opportunity表，以便它们在bus_id外键上链接？

Answer 1

首先为它们创建一个连接模型：

 bin/rails g migration create_businesses_opportunities 

现在，转到迁移文件并确保它看起来像这样：

 class CreateBusinessesOpportunities < ActiveRecord::Migration def change create_table :businesses_opportunities do |t| t.belongs_to :opportunity, index: true t.belongs_to :business, index: true end end end 

然后：

车型/ business.rb

 has_and_belongs_to_many :opportunities 

车型/ opportunity.rb

 has_and_belongs_to_many :businesses 

这样做是为每个模型添加一个“动态”属性，将ID存储到数组中。

例：

 #To have an opportunity belong to multiple businesses, say IDs 1, 2, and 3 @opp = Opportunity.find(1) @opp.update_attribute :business_ids, [1,2,3] @opp.businesses # => will now show the three businesses #The same works for associating a business to multiple opportunities, just the other way around @busn = Business.find(1) @busn.update_attribute :opportunity_ids, [1,2,3] @busn.opportunities # => will now show the three opportunities