通過STI使用has_many與多重模型類型

Question

如何使用通過STI繼承的兩種不同模型保存和查看has_many關係？

我已經得到了項目基本型號如下：

class Project < ActiveRecord::Base 
    attr_accessible :slug, 
        :category_id, 
        :description, 
        :name, 
        :visible, 
        :note, 
        :contractor, :contractor_url, 
        :date_complete, :architect, :architect_url, 
        :building_year, 
        :project_type, 
        :address, :city, :state, :country, 
        :pictures, 
        :photo_credit 

    has_many :pictures, :order=>:id, :dependent => :destroy 

Picture.rb：

class Picture < ActiveRecord::Base 
    attr_accessible :project_id, :image, :caption, :cover, :dimensions 

    belongs_to :project 

並採用STI我有顯示項目的一個子集，並具體首頁項目到主頁：

class HomepageItem < Project 
    attr_accessible :slug, 
        :name, 
        :visible, 
        :note, 
        :pictures, 
        :photo_credit 

    has_many :pictures, :order=>:id, :dependent => :destroy 

這會導致預期在圖片上出現新列的錯誤的代替project_id

PG::UndefinedColumn: ERROR: column pictures.homepage_item_id does not exist
I believe this should be looking on the pictures.project_id column.

注：如果沒有HomepageItem定義的has_many，該項目被保存，但是不會創建任何圖片。這也是一個Rails 3.2.22項目。

Answer 1

如您所見，尋找國外關鍵，所以包括像下面的關聯外鍵，

class HomepageItem < Project 
    attr_accessible :slug, 
        :name, 
        :visible, 
        :note, 
        :pictures, 
        :photo_credit 

    has_many :pictures, :foreign_key =>:project_id, :order=>:id, :dependent => :destroy