未定義的方法'各爲零：NilClass

我正在使用當前正在使用的系統，並且出現了不常使用的功能的錯誤。未定義的方法'各爲零：NilClass

NoMethodError in Offer_receipts#index 

Showing /Users....../app/views/offer_receipts/index.html.erb where line #8 raised: 

undefined method `each' for nil:NilClass 
Extracted source (around line #8): 

5:  <th>Patron</th> 
6:  <th>One Time Offer</th> 
7: </tr> 
8: <% for offer_receipt in @offer_receipts %> 
9:  <tr> 
10:  <td><p> popld</p></td> 
11:  <td><%= offer_receipt.patron_id %></td>

這個錯誤發生在這部分渲染當前顯示的頁面：

<h2>Offers</h2> 
<div id="offers"> 
<% if @offers.count > 0 %> 
< % @offers.each do |o| %> 
    <%= show_one_time_offer(o, @patron) %> 
    <% end %> 

<% else %> 
    <strong>There are no offers currently available</strong> 


<% end %> 
</div>

一旦一次報價被點擊，這個頁面加載，這是錯誤發生的頁面：

index.html.erb

<% title "Offer Receipts" %> 

<table> 
    <tr> 
    <th>Patron</th> 
    <th>One Time Offer</th> 
    </tr> 
    <% for offer_receipt in @offer_receipts %> 
    <tr> 
     <td><%= offer_receipt.patron_id %></td> 
     <td><%= offer_receipt.one_time_offer_id %></td> 
     <td><%= link_to "Show", offer_receipt %></td> 
     <td><%= link_to "Edit", edit_offer_receipt_path(offer_receipt) %></td> 
     <td><%= link_to "Destroy", offer_receipt, :confirm => 'Are you sure?', :method => :delete %></td> 
    </tr> 
    <% end %> 
</table> 

<p><%= link_to "New Offer Receipt", new_offer_receipt_path %></p>

這裏是定義其他兩個文件在一個時間內提供收據的方法和範圍

offer_receipt.rb

class OfferReceipt < ActiveRecord::Base 
    belongs_to :patron 
    belongs_to :one_time_offer 
    validates :patron, :presence=>true 
    validates :one_time_offer, :presence=>true 
    require 'offer_receipt_validator.rb' 
    validates_with OfferReceiptValidator 


end

offer_receipts_controller.rb

class OfferReceiptsController < ApplicationController 
    def create 
    begin 
     @patron = Patron.find(params[:patron]) 
    rescue ActiveRecord::RecordNotFound 
     flash[:error] = "You must provide a patron for an offer receipt" 
     redirect_to root_url 
     return 
    end 
    @offer_receipt = OfferReceipt.new(:patron_id=>params[:patron], :one_time_offer_id=>params[:one_time_offer]) 
    if @offer_receipt.save && @patron 
     redirect_to @patron, :notice => "Recorded offer receipt" 
    else 
     flash[:error] = "There was a problem saving your offer receipt" 
     redirect_to @patron 
    end 
    end 
end

有上市等事情完全一樣的其他index.html.erb文件爲每個循環，他們工作正常。我也檢查了數據庫，並有超過2000行，所以不能成爲問題。

來源

2012-09-28 user1707165

我沒有看到你OfferReceiptsController索引作用，這可能是問題。 – Wukerplank

在你的'OfferReceiptsController'中，你能顯示'index'動作嗎？看起來'@ offer_receipts'實例變量是nil。也許你沒有設置它？ – Zajn

您的實例變量@offer_receipt未在您的#index控制器操作中設置。

您應該添加#index操作。像這樣的東西應該工作：

class OfferReceiptsController < ApplicationController 
    def index 
    @offer_receipts = OfferReceipt.all 
    end 
end

，您還可以在#index動作添加額外的邏輯。例如，您可能想要將實例變量的範圍設置爲current_user。

@offer_receipts = OfferReceipt.where(:user_id => current_user.id)

來源

2014-11-20 03:07:37 sealocal

未定義的方法'各爲零：NilClass

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