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我试图允许用户将项目输入数据库。其中一个字段允许他们为该项目输入多种技术。

这是我的项目控制器，新建和创建操作。

def new
  @project = Project.new
  @all_technols = Technol.all
  @project_technol = @project.projecttechnols.build

  respond_to do |format|
    format.html # new.html.erb
    format.json { render json: @project }
  end
end

def create
  @project = Project.new(params[:project])
  params[:technols][:id].each do |technol|
    if !technol.empty?
      @project.projecttechnols.build(:technol_id => technol)
    end
  end
end

这是我的多选技术下拉列表的新项目视图。

<%= fields_for(@project_technol) do |ab| %>
  <div class="tech">
    <%= ab.label "All Tech" %><br/>
    <%= collection_select(:technols, :id, @all_technols, :id, :tech, {}, {:multiple => true} ) %>
  </div>
<% end %>

项目.rb

class Project < ActiveRecord::Base
  attr_accessible :tech
  has_many :projecttechnols
  has_many :technols, :through => :projecttechnols
end

技术.rb

class Technol < ActiveRecord::Base
  attr_accessible :tech
  has_many :projecttechnols
  has_many :projects, :through => :projecttechnols
end

工程技术.rb

class Projecttechnol < ActiveRecord::Base
  attr_accessible :project_id, :technol_id
  belongs_to :technol
  belongs_to :project
end

目前，我有一个页面，用户可以在其中输入一项新技术。但我想将此选项移至创建新项目页面，他们可以在其中选择现有技术，或输入新技术，或两者兼而有之，他们将与该项目一起保存。

但是，当我尝试保存一个新项目时，我收到了这个错误。

Showing /home/james/Desktop/webapp/app/views/projects/new.html.erb where line #233 raised:

    undefined method `model_name' for NilClass:Class

Extracted source (around line #233):

233: <%= fields_for(@project_technol) do |ab| %>
234: 
235: <div class="tech">
236: <%= ab.label "All Tech" %><br/>

我是 Rails 新手，还在学习，所以请记住回答。提前致谢。

编辑

改变后

@project.projecttechnols.build(:technol_id => technol)

至

@project_technol = @project.projecttechnols.build(:technol_id => technol)

我现在收到此错误：

NoMethodError in Projects#create

undefined method `map' for nil:NilClass

Extracted source (around line #240):

237: <div class="tech">
238: <%= ab.label "All Tech" %><br/>
239: 
240: <%= collection_select(:technols, :id, @all_technols, :id, :tech, {}, {:multiple => true} ) %>
241: </div>
242: <% end %>

编辑 2

@all_technols = 创建操作中的 Technol.all

我现在得到这个错误。

NoMethodError in Projects#show

Showing /home/james/Desktop/webapp/app/views/projects/show.html.erb where line #181 raised:

undefined method `technol' for #<Project:0xb36823c>
Extracted source (around line #181):

178: <h3>Related books</h3>
179: 
180: <ul>
181:   <% @project.technol.each do |technol| %>
182:     <li><%= technol.tech %> <%= link_to "Details", technol_path(technol) %></li>
183:   <% end %>
184: </ul>
4

1 回答 1

2

您的create操作正在再次渲染new视图。但是，@project_technol在create动作中没有定义。该方法在 ( ) 中传递的参数上fields_for调用方法，但由于，它会抛出该错误。要解决此问题，请在您的操作中更改model_name@project_technol@project_technol = nilcreate

@project.projecttechnols.build(:technol_id => technol)

至

@project_technol = @project.projecttechnols.build(:technol_id => technol)
于 2012-09-27T11:29:24.597 回答