Ruby on rails RubyonRails：在编辑页面上不保存数据的字段

我有一个应用程序，用户可以提交一个新的项目。提交一个项目后，他们可以选择编辑刚刚提交的项目。单击edit（编辑）时，它会再次显示表单，并显示以前输入的所有数据

我的问题在于其中一个字段，它允许用户选择许多技术。它链接到另一个名为Projecttechnol的表，该表保存Technol表和Project表之间的链接。当用户单击编辑按钮时，该项目中包含的所有技术都不会显示。如果用户单击一项新技术并保存，则新技术将被保存，而旧技术仍然存在

我的技术编辑视图：

我是rails新手，因此任何帮助都将不胜感激，提前感谢

更新：这是我的项目模型

class Project < ActiveRecord::Base
  attr_accessible  :fullname, :edited_first_name, :edited_last_name, :first_name, :last_name, :business_div, :client, :customer_benefits, :edited_date, :end_date, :entry_date, :financials, :industry, :keywords, :lessons_learned, :project_name, :project_owner, :role, :start_date, :status, :summary, :tech , :technols, :technol_tokens

has_many :projecttechnols
has_many :technols, :through => :projecttechnols

accepts_nested_attributes_for(:technols)

---

另外，请确保您的项目包含与嵌套模型的正确关系，并且它已接受您在集合中设置的

的

属性：multiple=>true。

我需要允许他们选择多个技术感谢帮助。我把我的代码改成了你的，结果我出错了。这些技术仍然没有出现，当我尝试添加更多时，会出现以下错误：nil:NilClass的未定义方法[]。我已经更新了我的问题，所以你可以看到我的模型。你好，我仍然得到相同的错误。ProjectsControllerupdate中的NoMethodError，未定义nil:NilClass的方法[]。我已将我的参数添加到我的问题中。请将代码放入更新方法中，并告诉我们哪一行出现上述错误！

def new

  @project = Project.new
  @technol = Technol.new(params[:tech])

  @all_technols = Technol.all
  tech_ids = params[:technols][:id].reject(&:blank?) unless params[:technols].nil?


  @project_technol = @project.projecttechnols.build

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

def edit
    @project = Project.find(params[:id])


@project_technol = @project.projecttechnols.build


  end

def create  
    @project = Project.new(params[:project])
    @project.client = params[:new_client] unless params[:new_client].blank?
    @technol.tech = params[:new_tech] unless params[:new_tech].blank?
    @project.role = params[:new_role] unless params[:new_role].blank?

    params[:technols][:id].each do |tech|


    if !tech.empty?

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

end

end

    respond_to do |format|
      if @project.save
        format.html { redirect_to @project, notice: 'Project was successfully created.' }
        format.json { render json: @project, status: :created, location: @project }
      else
        format.html { render action: "new" }
        format.json { render json: @project.errors, status: :unprocessable_entity }
      end
    end
  end

def update
    @project = Project.find(params[:id])
    @project.client = params[:new_client] unless params[:new_client].blank?
    @technol.tech = params[:new_tech] unless params[:new_tech].blank?
    @project.role = params[:new_role] unless params[:new_role].blank?

     params[:technols][:id].each do |tech|

     if !tech.empty?
     @project_technol = @project.projecttechnols.build(:technol_id => tech) 

  end
  end
    respond_to do |format|
      if @project.update_attributes(params[:project])
        format.html { redirect_to @project, notice: 'Project was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @project.errors, status: :unprocessable_entity }
      end
    end
  end

class Project < ActiveRecord::Base
  attr_accessible  :fullname, :edited_first_name, :edited_last_name, :first_name, :last_name, :business_div, :client, :customer_benefits, :edited_date, :end_date, :entry_date, :financials, :industry, :keywords, :lessons_learned, :project_name, :project_owner, :role, :start_date, :status, :summary, :tech , :technols, :technol_tokens

has_many :projecttechnols
has_many :technols, :through => :projecttechnols

accepts_nested_attributes_for(:technols)

{"utf8"=>"✓",
 "_method"=>"put",
 "authenticity_token"=>"+Fdh61iVz2IqZ+bNQz9SIa5ly7nNXaiCEr28hVWUxpM=",
 "project"=>{"project_name"=>"Beverly",
 "status"=>"Completed",
 "client"=>"Qtjpa",
 "business_div"=>"Ecbly",
 "project_owner"=>"Qpzrv",
 "start_date"=>"2012-10-15",
 "edited_date"=>"2012-10-08",
 "projecttechnols"=>{"id"=>["",
 "41"]},
 "role"=>"Ozeoe",
 "industry"=>"Wjfiq",
 "summary"=>"Eypriw lorem ipsum dolor sit amet,
 consectetur adipisicing elit,
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 "lessons_learned"=>"Kbjuhy lorem ipsum dolor sit amet,
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 sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
 "customer_benefits"=>"Fsonlw lorem ipsum dolor sit amet,
 consectetur adipisicing elit,
 sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",,
 "keywords"=>"Bwdtm"},
 "new_client"=>"",
 "new_business_div"=>"",
 "new_project_owner"=>"",
 "new_role"=>"",
 "new_industry"=>"",
 "commit"=>"Save Edit",
 "id"=>"103"}

<%= fields_for(@project_technol) do |ab| %>
  <%= ab.label "Choose Technologies"%> </br>
  <%= collection_select( :technols, :id, Technol.all, :id, :tech, {}, {:multiple => true } ) %>
<% end %>

<%= f.fields_for(:projecttechnols) do |ab| %>
  <%= ab.label "Choose Technologies"%> </br>
  <%= ab.collection_select(:id, Technol.all, :id, :tech, {}, {:multiple => true } ) %>
<% end %>

form_for(@project) do |f|