未定义的方法`+'代表nil：NilClass（NoMethodError） - Ruby

Question

当运行rails应用程序时，我得到以下错误，该错误在图像中清晰显示，如下所示;

index.html.erb

<% balance = 0 %>

<div class="row">

    <div class="col-md-10 col-md-offset-1">

        <div class="table-responsive myTable">

            <table class="table listing text-center">
                <tr class="tr-head">
                    <td>Date</td>
                    <td>Description</td>
                    <td>Amount</td>
                    <td>Discount</td>
                    <td>Paid</td>
                    <td>Balance</td>
                </tr>

                    <%= render partial: "xvaziri", collection: @xvaziris %>

                </table>
            </div>
        </div>
    </div>

_xvaziri.html.erb

<tr  class="tr-<%= cycle('odd', 'even') %>">

    <td class="col-1"><%= xvaziri.date.strftime('%d/%m/%Y') %></td>
    <td class="col-3"><%= span_with_possibly_red_color xvaziri.description %></td>


    <td class="col-1"><%= number_with_precision(xvaziri.amount, :delimiter => ",", :precision => 2) %></td>

    <td class="col-1 neg"><%= number_with_precision(xvaziri.discount, :delimiter => ",", :precision => 2) %></td>

    <td class="col-1 neg"><%= number_with_precision(xvaziri.paid, :delimiter => ",", :precision => 2) %></td>


    <% balance += xvaziri.amount.to_f - xvaziri.discount.to_f - xvaziri.paid.to_f %>

    <% color = balance >= 0 ? "pos" : "neg" %>

    <td class="col-1 <%= color %>"><%= number_with_precision(balance.abs, :delimiter => ",", :precision => 2) %></td>

</tr>

欢迎任何建议。

提前谢谢。

Answer 1

您正在使用部分中索引视图本地的变量，该变量无法访问它。将其作为局部传递给部分：

<%= render partial: "xvaziri", collection: @xvaziris, balance: balance %>

或将其提供给整个请求

<% @balance = 0 %>

我会推荐后者，因为你会在很多地方使用它。将变量的所有用法更新为@balance，您就可以设置了。