未定义的方法“ +”，用于nil：NilClass（NoMethodError）-Ruby

Question

When the rails application is run, I get the following error which is shown clearly in an image, which is as below;

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>

Any suggestions are most welcome.

Thank you in advance.

Answer 1

You're using a variable that is local to the index view in the partial, which has no access to it. Either pass it through as a local to the partial:

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

or make it available to the whole request

<% @balance = 0 %>

I would recommend the latter since you will be using it in many places. Update all uses of the variable to @balance and you'll be set.