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我正在使用旧数据库，并且还在阅读 Rails的关联指南。

我有两个模型。一个diary模型和一个animal模型。

日记.rb

class Diary < ActiveRecord::Base
  establish_connection :premvet

  attr_accessible :DiaryNo ,:DiaryName, :DiaryDate, :SlotHour, :TotalSlots, :BlockSlots, :BlockBooked, :FreeSlot, :BookedSlot

  self.table_name = 'diary'
  self.primary_key = 'DiaryNo'

  has_many :animals, :foreign_key => 'DiaryQueue'
end

动物.rb

class Animal < ActiveRecord::Base
  establish_connection :premvet

  self.table_name = 'animal'
  self.primary_key = 'PVID'

  attr_accessible :AddedBy, :Age, :AnimalBFAmount, :AnimalBalance, :AnimalName, :Archive, :BillType, :Breed, :ChronicStatus, :Class, :Classification, :ClientKey, :Colour, :Date1, :DateOfBirth, :DateofBirth, :Dead, :DiaryQueue, :DiscField, :DrugsAtCost, :DrugsNoVAT, :ESDAmount, :ESDType, :FNote, :FirstRegisteredDate, :Height, :IDNumber, :Insured, :InsuredWith, :IsClient, :IsClientDate, :IsMaster, :LastBilledAmount, :LastBilledDate, :LastConsDate, :LastContributionDate, :LastPaidDate, :LastWeightDate, :Locked, :LoyaltyMultiplier, :LoyaltyPoints, :MR_Flag_0, :MR_Flag_1, :MR_Flag_10, :MR_Flag_11, :MR_Flag_12, :MR_Flag_13, :MR_Flag_14, :MR_Flag_15, :MR_Flag_2, :MR_Flag_3, :MR_Flag_4, :MR_Flag_5, :MR_Flag_6, :MR_Flag_7, :MR_Flag_7, :MR_Flag_8, :MR_Flag_9, :Mileage, :Neutered, :NextApptDate, :ORT, :OldSex, :Opt_Flag_0, :Opt_Flag_1, :Opt_Flag_2, :Opt_Flag_3, :Opt_Flag_4, :Opt_Flag_5, :Opt_Flag_6, :Opt_Flag_7, :PVID, :PreferredContact, :PreferredUser, :Ref1, :RefPrac, :ReferredBy, :SSDType, :SeenInPeriod, :SendBill, :Sex, :SiteAnimal, :Species, :Status, :SurcAmount, :SurcType, :SurgeryNumber, :TBU, :TOSAmount, :TOSDrugs, :TOSFees, :TOSType, :Weight

  belongs_to :client, :foreign_key => 'ClientKey'
  belongs_to :diary, :foreign_key => 'DiaryNo'
end

动物索引视图

<% @animals_todaysappointments.each do |animal| %>
  <tr>
    <td><%= animal.id %></td>    
    <td><%= animal.AnimalName %></td>
    <td><%= link_to animal.client.Surname, animal.client %></td>    
    <td><%= animal.Species %></td>
    <td><%= animal.Breed %></td>
    <td><%= animal.NextApptDate.strftime("%d %b. %Y -  %H:%M") %></td>        
    <td><%= animal.DiaryQueue %>
    <td><%= animal.diary.DiaryName %></td>    
    <td><%= link_to 'Show', animal %></td>
  </tr>
<% end %>

如您所见，它使用以下方法显示动物表中的 DiaryQueue：

<td><%= animal.DiaryQueue %>

我正在尝试显示日记表中的 DiaryName：

<td><%= animal.diary.DiaryName %></td>

这失败并出现异常错误：

undefined method `DiaryName' for nil:NilClass

该@animals_todaysappointments方法如下所示：

def appointments
    @animals_todaysappointments = Animal.where('DATE(NextApptDate) = ?', Date.today).page(params[:page]).per_page(15).order('NextApptDate ASC')
    respond_to do |format|
      format.html # index.html.erb
    end
  end

如果我添加：

delegate :DiaryName, :to => :diary

到动物模型然后我得到以下错误：

Animal#DiaryName delegated to diary.DiaryName, but diary is nil: #

每条动物记录都有一个介于 0 和 10 之间的 DiaryQueue 值，并且日记表有许多行，示例行是：

DiaryNo  DiaryName  DiaryDate  SlotHour  TotalSlots  BlockBooked  FreeSlot  BookedSlot
--------------------------------------------------------------------------------------
1        Morning    2012-07-16 9         18          0            0         18

有些行具有相同的 DiaryNo，但它们也具有相同的 DiaryName。只有 DiaryDate、SlotHour、TotalSlots、BlockBooked、FreeSlot 和 BookedSlot 在这些行中发生变化。

为了尝试防止错误，我在视图中添加了以下内容：

<% unless animal.DiaryName.nil? %>
 <td><%= animal.DiaryName %></td>
<% else %>
 <td><%= animal.DiaryQueue %>
<% end %>

但我得到一个例外：

Animal#DiaryName delegated to diary.DiaryName, but diary is nil: #

我究竟做错了什么？

4

1 回答 1

1

鉴于您上面的答案，您可能需要将 Animal 中的 belongs_to 方法更改为以下内容：

belongs_to :diary, :foreign_key => "DiaryQueue", :primary_key => "DiaryNo"

在您当前的实现中，您的模型将尝试匹配Animal#DiaryNo，Diary#DiaryNo而您所说的要Animal#DiaryQueue匹配Diary#DiaryNo。

于 2012-08-09T12:20:16.990 回答