rails 3未定义的方法`update_attributes'为零：NilClass

问题描述：

我刚接触Ruby和rails。我正在做一个更新的形式：硬件数据库中的所有者值。使用自定义视图名称transfer.html.erb。我的表单代码显示在下面。rails 3未定义的方法`update_attributes'为零：NilClass

<%= form_for @hardware, :url => do_transfer_path do |f| %>

这是hardwares_tranfers_controller.rb

def transfer 
    @hardware = Hardware.find(params[:id]) 
    if current_user.user_lvl == 0 
    @users = User.order(:user_lvl) 
    else 
    @users = User.where(:refer => current_user.id) 

    respond_to do |format| 
    format.html # index.html.erb 
    format.json { render json: @hardwares } 
    end 
    end 
end 


def do_transfer 
# transfer_user = User.where(:id => @hardware.owner).email 
#  TransferLog.create([:user_id => current_user.id, :hardware_id => @hardware.id]) 
    if @hardware.update_attributes(params[:hardware]) 
    format.html { redirect_to users_url, notice: "Hardware was successfully transfer"} 
    format.json { head :no_content } 
    else 
    format.html { render action: "edit" } 
    format.json { render json: @hardware.errors, status: :unprocessable_entity } 
    end 
end

我的自定义控制器和我得到的错误是 NoMethodError在HardwaresTransfersController＃do_transfer 未定义的方法update_attributes' for nil:NilClass Aplication Traces app/controllers/hardwares_transfers_controller.rb:23:in do_transfer”

参数

{"utf8"=>"✓", 
"_method"=>"put", 
"authenticity_token"=>"vkwKyuS4eviRN1ogrpOcGh1Y5OBNX0wiBzpV8taNkq0=", 
"hardware"=>{"owner"=>"3"}, 
"commit"=>"Transfer Hardware"}

条

我的routes.rb

match "hardwares_transfers/" => "hardwares_transfers#do_transfer" , :as => :do_transfer 
get "hardwares_transfers/:id/transfer" => "hardwares_transfers#transfer", :as => :transfer_hardwares

耙路线>

 do_transfer  /hardwares_transfers(.:format)    hardwares_transfers#do_transfer 
transfer_hardwares GET /hardwares_transfers/:id/transfer(.:format) hardwares_transfers#transfer 
     hardwares GET /hardwares(.:format)      hardwares#index 
        POST /hardwares(.:format)      hardwares#create 
     new_hardware GET /hardwares/new(.:format)     hardwares#new 
    edit_hardware GET /hardwares/:id/edit(.:format)    hardwares#edit 
      hardware GET /hardwares/:id(.:format)     hardwares#show 
        PUT /hardwares/:id(.:format)     hardwares#update 
        DELETE /hardwares/:id(.:format)     hardwares#destroy

答

你需要

def do_transfer 
    @hardware = Hardware.find(params[:id]) 
    ... 
end

我还要借此机会指出的是，你很可能在这个框架更多REST -ful的方式

确定...当我再补充一点行它表明这个错误引发ArgumentError在HardwaresController＃do_transfer 太少论据 – 2012-02-01 07:06:55

谢谢我发现了这个问题... – 2012-02-01 07:54:25

答

错误是NoMethodError in HardwaresTransfersController#do_transfer
未定义的方法update_attributes'为零：NilClass。

正如错误所述，Rails正试图在nil：NilClass上调用update_attributes，这意味着您的@hardware对象为零。
所以，你应该

@hardware = Hardware.find(params[:id])

你应该总是看的错误，并给它一个念头，为什么这个错误是没有初始化它，它会帮助你学习更好。

好的...我解决了，但即时通讯太少参数错误 – 2012-02-01 07:25:41

答

发现硬件项目：

def do_transfer 
    @hardware = Hardware.find(params[:id]) 
    ... 
end

和变化route.rb：

match "hardwares_transfers/:id" => "hardwares_transfers#do_transfer" , :as => :do_transfer

不工作...得到HardwareSController＃ArgumentError o_transfer =参数太少 – 2012-02-01 07:24:53

谢谢我发现问题.. – 2012-02-01 07:54:54

rails 3未定义的方法`update_attributes'为零：NilClass

相关推荐