Rails，是否可以根据包含余额的表的列值更改颜色？

Question

index.html.erb

<% balance = 0 %> 

    <table align="center" width="50%" cellpadding="1" cellspacing="5"> 
     <tr> 
      <td>Amount</td> 
      <td>Discount</td> 
      <td>Paid</td> 
      <td>Balance</td> 
     </tr> 

<% @statements.each do |statement| %> 

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

    <td class="col-1"><%= statement.date %></td> 
    <td class="col-3"><%= statement.description %></td> 

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

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

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


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

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

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

</tr> 

    <% end %> 

    </table> 

<center><p><b><%= number_to_currency(balance.abs, :unit => 'AED ', :delimiter => ",", :precision => 2) %></b></p></center> 

我想有一个是平衡实体的颜色变化时余额是正就必须表现出黑色和变负时，它必须显示为红色。

这里是我的application.css.scss

.pos { color: #000; } 
.neg { color: #f00; } 

我没有得到的结果如预期。

请看下面的结果;

Sample data

picture

Answer 1

里克是正确的，但有一个小故障。

正如我在上面的评论中提到的那样，在计算新值之前，正在使用余额值来分配类.neg or .pos。这是负责它采取以前的balance价值给它的类如附件中所示的样本。

下面是你如何使用它来得到它正常工作之前计算出新的价值：

<% balance = 0 %> 

<table align="center" width="50%" cellpadding="1" cellspacing="5"> 
    <tr> 
     <td>Amount</td> 
     <td>Discount</td> 
     <td>Paid</td> 
     <td>Balance</td> 
    </tr> 

    <% @statements.each do |statement| %> 

    <tr> 

     <td><%= statement.amount %></td> 

     <td class="neg"><%= statement.discount %></td> 
     <td class="neg"><%= statement.paid %></td> 

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

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

     <td class="<%= color %>"><%= balance %></td> 

    </tr> 

    <% end %> 

</table> 

发现，我们首先在任何操作在使用它之前计算的balance新值。这样，在分配课程时，balance保留了当前循环的真实和正确的值。

试试这个，让我们知道你在视图上得到了什么......

Answer 2

当然，just use CSS：

#app/assets/stylesheets/application.css 
tr.pos { color: #000; } 
tr.neg { color: #f00; } 

#app/views/controller/index.html.erb 
<% color = balance >= 0 ? "pos" : "neg" %> 

<td class="col-1 <%= color %>"><%= number_with_precision(statement.discount, :delimiter => ",", :precision => 2) %></td> 
<td class="col-1 <%= color %>"><%= number_with_precision(statement.paid, :delimiter => ",", :precision => 2) %></td> 
<td class="col-1 <%= color %>"><%= number_with_precision(balance += statement.amount.to_f - statement.discount.to_f - statement.paid.to_f, :delimiter => ",", :precision => 2) %></td>