Rails 4甲骨文增强适配器很多很多问题

Question

第一件事

使用：

• rails4
• oracle增强适配器rails4分支

我在现有数据库上映射了许多到多个关系。我的模特看起来是这样的：

class EventMap < ActiveRecord::Base
  self.table_name="TAKE_PART"
  self.primary_key="id"
  belongs_to :event, foreign_key: "lottery_event_id"  
  belongs_to :entrant, foreign_key: "address_id"  
end

class Event < ActiveRecord::Base
  self.table_name="THE_EVENT"
  self.primary_key="id"
  has_many :event_maps
  has_many :entrants, :through => :event_maps
end

class Entrant < ActiveRecord::Base
  self.table_name="ADDRESSES"
  self.primary_key="id"
  self.set_date_columns :date_of_birth
  has_many :event_maps
  has_many :events, :through => :event_maps
end

当我试图获取事件的所有地址时：

  def show
    @entrants = Event.find(params[:id]).entrants
  end

我得到了这样一个Oracle错误：

OCIError: ORA-00904: "TAKE_PART"."ENTRANT_ID": SELECT "THE_EVENT".* FROM "THE_EVENT" INNER JOIN "TAKE_PART" ON "THE_EVENT"."ID" = "TAKE_PART"."LOTTERY_EVENT_ID" WHERE "TAKE_PART"."ENTRANT_ID" = :a1

这里的问题似乎是TAKE_PART的外键使用不当，应该是address_id，而是使用模型名entrant_id。

这是oracle中的一个bug增强了，还是我在表的匹配上做错了什么？

Answer 1

类的关联还没有完全定义，bc Event和Entrant都不知道正确的ids，它们应该传递给EventMap。适当的办法如下：

class EventMap < ActiveRecord::Base
  ...
  belongs_to :event, :foreign_key => "lottery_event_id"  
  belongs_to :entrant, :foreign_key => "address_id"
end

class Event < ActiveRecord::Base
  ...
  has_many :event_maps, :foreign_key => "lottery_event_id"
  has_many :entrants, :through => :event_maps
end

class Entrant < ActiveRecord::Base
  ...
  has_many :event_maps, :foreign_key  => "address_id"
  has_many :events, :through => :event_maps
end

它之所以有效，是因为event.entrants意味着对数据库(简化)执行以下操作：

连接两个表EventMap和Entrant，以便address_id <=> entrant.id (映射1) 在联接表中查找所有具有lottery_event_id = event.id (映射2)的字符串

映射1

has_many :entrants, :through => :event_maps         #Join two tables
belongs_to :entrant, :foreign_key => "address_id"   #matching address_id with entrants.id
#belongs_to+foreign_key tells to EventMap which key to use for referring to Event object

映射2

has_many :event_maps, :foreign_key => "lottery_event_id" #associate event.id with lottery_event_id
#has_many+foreign_key tells to Event which key EventMap uses for referring to Event object

或以更正式的方式：

SELECT "entrants".* FROM "entrants" INNER JOIN "event_maps" ON "entrants"."id" =
"event_maps"."address_id" WHERE "event_maps"."lottery_event_id" = ?  [["lottery_event_id", 1]]