G'day伙计们，
我目前正在建立一个测试“拍卖”网站以学习铁路。我已经设置了我的拍卖和用户模型，并且只有经过身份验证的用户才能编辑或删除与他们相关的拍卖。
我遇到的困难是将出价项与拍卖相关联。
我的模型如下：
class Auction < ActiveRecord::Base
belongs_to :creator, :class_name => "User"
has_many :bids
validates_presence_of :title
validates_presence_of :description
validates_presence_of :curprice
validates_presence_of :finish_time
attr_reader :bids
def initialize
@bids = []
end
def add_bid(bid)
@bids << bid
end
end
class Bid < ActiveRecord::Base
belongs_to :auction, :class_name => "Auction", :foreign_key => "auction_id"
belongs_to :bidder, :class_name => "User", :foreign_key => "bidder_id"
validates_presence_of :amount
validates_numericality_of :amount
@retracted = false
end
class User < ActiveRecord::Base
has_many :auctions, :foreign_key => "owner_id"
has_many :bids, :foreign_key => "owner_id"
#auth stuff here
end
我正在尝试为竞价添加出价记录，但auction_id根本不会添加到记录中。
<% form_for :bid, :url => {:controller => "auction", :action => "add_bids"} do |f|%>
<p>Bid Amount <%= f.text_field :amount %></p>
<%= submit_tag "Add Bid", :auction_id => @auction %>
<% end %>
这与以下代码相关：
def add_bids
@bid = current_user.bids.create(params[:bid])
if @bid.save
flash[:notice] = "New Bid Added"
redirect_to :action => "view_auction", :id => @bid.auction_id
end
end
我得到的问题是auction_id没有放入bid元素。我尝试用HTML格式设置它，但我想我错过了很简单的东西。
我的数据模型，回顾一下
用户同时拥有出价和拍卖
拍卖会有用户并且有很多出价
出价有用户并有拍卖
在过去的4个小时里，我一直在努力解决这个问题，而且我开始对这一切感到非常失望。
任何帮助都会非常感激！
答案 0 :(得分：9)
你并没有完全按照Rails的方式做事，这让你有点混乱。 在Rails中成功编码完全是关于约定优于配置。意思是，Rails会猜测你的意思，除非你另有说明。如果猜错了，通常会尝试一些事情。但总的来说，坚持确定性名称，你会没事的。
你的代码中有很多错误，所以我要清理它并以各种方式发表评论，让你知道什么是错的。
应用/模型/ auction.rb
class Auction < ActiveRecord::Base
belongs_to :creator, :class_name => "User"
has_many :bids
# Given the nature of your relationships, you're going to want to add this
# to quickly find out who bid on an object.
has_many :bidders, :through => :bids
validates_presence_of :title
validates_presence_of :description
validates_presence_of :curprice
validates_presence_of :finish_time attr_reader :bids
#These two methods are unnecessary.
# Also don't override initialize in ActiveRecord. Instead use after_initialize
#def initialize Supplied by rails when you do has_many :bids
# @bids = [] @bids will be populated by what is picked up from
#end the database based on the has_many relationship
#def add_bid(bid) Supplied by rails when you do has_many :bids
# @bids << bid auction.bids << is a public method after has_many :bids
#end
end
应用/模型/ bid.rb
class Bid < ActiveRecord::Base
# :class_name and :foreign_key are ony necessary when rails cannot guess from a
# association name. :class_name default is the association singularized and
# capitalized. :foreign_key default is association_id
belongs_to :auction #, :class_name => "Auction", :foreign_key => "auction_id"
# here we need :class_name because Rails is looking for a Bidder class.
# also there's an inconsistency. Later user refers to has_many bids with
# a foreign_key of owner_id, which one is it? bidder_id or owner_id?
# if it's owner_id? you will need the :foreign_key option.
belongs_to :bidder, :class_name => "User" #, :foreign_key => "bidder_id"
validates_presence_of :amount
validates_numericality_of :amount
# This will never get called in a useful way.
# It really should be done in the migration, setting default
# value for bids.retracted to false
# @retracted = false
end
app / models / user.rb
class User < ActiveRecord::Base
# This makes sense, because an auction can have many bidders, who are also users.
has_many :auctions, :foreign_key => "owner_id"
# This doesn't. A bid belongs to a user, there's no need to change the name.
# See above note re: owner_id vs. bidder_id
has_many :bids, :foreign_key => "owner_id"
# You could also use this to quickly get a list of auctions a user has bid on
has_many :bid_on_auctions, :through => :bids, :source => :auction
... auth stuff ...
end
到目前为止一切顺利，对吧？
视图不错，但它缺少出价金额的表单部分。此代码假定您将出价值存储在金额列中。我也随意命名为auction / bid
应用/视图/拍卖/ bid.html.erb
<% form_for :bid, @auction.bids.new do |f|%>
<%= f.label_for :amount %>
<%= f.text_field :amount%>
<!-- Don't need to supply @auction.id, because form_for does it for you. -->
<%= submit_tag "Add Bid" %>
由表单生成的params哈希：传递给控制器：
params =
{
:bid =>
{
:auction_id => @auction.id
:amount => value of text_field
}
}
你写的时候由from生成的params哈希（注意：我猜的是名字，因为它们被遗漏在发布的代码之外）：
params =
{
:id => @auction_id ,
:bid => { :amount => value of text_field }
}
但是，您的控制器代码是您所有问题的来源，几乎完全错误。我猜这是在拍卖控制器中，这似乎是错误的，因为你正试图创建一个出价。让我们看看为什么：
应用/控制器/ auctions_controller.rb
...
def add_bids
# not bad, but... @bid will only fill in the owner_id/bidder_id. and bid amount.
@bid = current_user.bids.create(params[:bid])
# create calls save, so this next line is redundant. It still works though.
# because nothing's happening between them to alter the outcome of save.
if @bid.save
flash[:notice] = "New Bid Added"
# you should be using restful routes, this almost works, but is ugly and deprecated.
# it doesn't work becasue @bid.auction_id is never set. In fact you never use
# the auction_id any where, which was in your params_hash as params[:id]
redirect_to :action => "view_auction", :id => @bid.auction_id
end
end
...
以下是控制器的工作方式。首先，这应该在bid_controller中，而不是auctions_controller
应用/控制器/ bids_controller.rb
...
def create
@bid = Bid.new(params[:bid]) # absorb values from form via params
@bid.bidder = current_user # link bid to current_user.
@auction = bid.auction based on.
# @auction is set, set because we added it to the @bid object the form was based on.
if @bid.save
flash[:notice] = "New Bid Added"
redirect_to @auction #assumes there is a show method in auctions_controller
else
render "auctions/show" # or what ever you called the above view
end
end
...
你还需要确保你的routes.rb中有以下内容（除了可能已存在的内容。这几行将为你设置RESTful路由。
<强>配置/ routes.rb中
ActionController::Routing::Routes.draw do |map|
...
map.resources :auctions
map.resources :bids
...
end
无论如何你离我不远了。看起来你有一个不错的开始，并且可能会从阅读有关rails的书中获益。如果您不理解底层框架，只是盲目地遵循教程对您没有多大帮助。 90％的教程都适用于较旧版本的rails并且已经过时了。
很多代码都是旧的做事方式。特别是redirect_to :action => "view_auction", :id => @bid.auction_id和<% form_for :bid, :url => {:controller => "auction", :action => "add_bids"} do |f|%>。使用RESTful路由，它们变为redirect_to @auction和＆lt;％form_for @ auction.bid.new do | f | ％GT;`
以下是您应该阅读的资源：