我如何在Rails3中实现父子关系 [英] how can i implement parent-child relationship in rails3
问题描述
我正在用rails3创建一个计费应用程序,在创建计费时我很困惑.
I'm creating a billing application in rails3, I have a confusion when it comes to creating a bill.
一个帐单可以包含一个或多个项目
one bill can have one or more items
'bill' has many 'items'
'item' belongs to 'bill'
我的要求如下
我应该能够创建新帐单并向其添加项目(可以添加任意数量的项目)
I should be able to create a new bill and add items to it (any number of items can be added)
我的问题是
1-要使项目保存在bill_details表中,我首先应生成bill_id,什么是生成此Bill ID的最佳方法.
1 - to get items to be saved in the bill_details table I should first generate bill_id, What is the best way to generate this bill id.
2-实现这种情况的最佳方法是什么
2 - what is the best way to implement a scenario like this
3-我可以从Rails嵌套表单中获得任何帮助吗
3 - can i get any help from rails nested forms
谢谢
欢呼 sameera
cheers sameera
推荐答案
在这种情况下,您应该使用多态关联.您可以在此处实现此目的:
You should use polymorphic association in this scenario. Here what you can do to achieve this:
在bill.rb#模型文件中:
in bill.rb # model file:
class Bill < ActiveRecord::Base
has_many :items # establish association with items!
# to save items in bill only if they are there!
accepts_nested_attributes_for :items, :allow_destroy => :true,
:reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
end
在item.rb#模型文件中:
in item.rb # model file :
class Item < ActiveRecord::Base
belongs_to :bill # establish association with bill!
end
在您的bills_controller.rb中创建常规操作:index, new, create, show, edit, update, delete
进行更新操作:
In your bills_controller.rb create normal actions : index, new, create, show, edit, update, delete
for update action:
def update
@bill = Bill.find(params[:id])
respond_to do |format|
if @bill.update_attributes(params[:bill])
format.html { redirect_to(@bill, :notice => 'Bill was successfully updated.') }
format.xml { head :ok }
else
format.html { render :action => "edit" }
format.xml { render :xml => @bill.errors, :status => :unprocessable_entity }
end
end
end
,您无需费心在items_controller.rb中创建任何action/方法,只需在view/Items/_form.html.erb中创建部分_form.html.erb并将其放置在此即可:
and you don't have to bother to create any action/ method in your items_controller.rb, just create a partial _form.html.erb in view/Items/_form.html.erb and put this:
<%= form.fields_for :items do |item_form| %>
<div class="field">
<%= tag_form.label :name, 'Item:' %>
<%= tag_form.text_field :name %>
</div>
<div class="field">
<%= tag_form.label :quantity, 'Quantity:' %>
<%= tag_form.text_field :quantity %>
</div>
<% unless item_form.object.nil? || item_form.object.new_record? %>
<div class="field">
<%= tag_form.label :_destroy, 'Remove:' %>
<%= tag_form.check_box :_destroy %>
</div>
<% end %>
<% end %>
现在,您必须从view/bills/_form.html.erb中调用它:
Now you have to call this from your view/bills/_form.html.erb:
<% @bill.tags.build %>
<%= form_for(@bill) do |bill_form| %>
<% if @bill.errors.any? %>
<div id="errorExplanation">
<h2><%= pluralize(@bill.errors.count, "error") %> prohibited this bill from being saved:</h2>
<ul>
<% @bill.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= bill_form.label :name %><br />
<%= bill_form.text_field :name %>
</div>
<h2>Items</h2>
<%= render :partial => 'items/form',
:locals => {:form => bill_form} %>
<div class="actions">
<%= bill_form.submit %>
</div>
<% end %>
View/Bills/new.html.erb:
View/Bills/new.html.erb:
<h1>New Bill</h1>
<%= render 'form' %>
<%= link_to 'Back', bills_path %>
View/Bills/edit.html.erb:
View/Bills/edit.html.erb:
<h1>Editing Bill</h1>
<%= render 'form' %>
<%= link_to 'Show', @bill %> |
<%= link_to 'Back', bills_path %>
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