Rails 3.从数组中获取总数

我正在打印一个包含行总数的表格，但我也希望获得总列数。 以下代码不起作用，而不是总计，它只打印出最后一次迭代的值。

                    Totals      

Answer 1

您的代码不起作用的原因是您的变量是在块中定义的，因此它们被视为块本地变量。 退出块后，这些变量将被标记为清除; 每次迭代都会重新定义这些变量。 在每次迭代中将它们重新分配给0也没有帮助，但这在这里甚至没有生效，因为每次都没有定义变量。

您可以在块之前简单地定义变量，但这仍然非常混乱。 由于Ruby习语和惯例强调清晰且组织良好的代码，我会偏离它，而是分别计算这些数字，可能在你的控制器中。

 @totals = { :overall => @shipments.reduce(0) { |total, shipment| total + shipment.invoice.customer_total }, :paid => @shipments.reduce(0) { |total, shipment| total + shipment.invoice.customer_amount_paid }, :balance => @shipments.reduce(0) { |total, shipment| total + shipment.invoice.customer_open_balance } } 

然后，您可以在装运表输出后执行以下操作，而不是使用@shipments.last比较：

   Totals <%= number_to_currency @totals[:overall] %> <%= number_to_currency @totals[:paid] %> <%= number_to_currency @totals[:balance] %>  

Answer 2

每次循环都将总计设置为零。 在循环之前移动初始化。

Answer 3

你可以使用rubyinject

就像是

 @shipments.inject(0) { |sum, shipment| sum + shipment.invoice.customer_total } 

或者为了保持代码布局，只需在@shipments.each循环之外初始化grand_customer_*对象，因为每次都要重置它们

Answer 4

 <% grand_customer_total = 0 grand_customer_amount_paid = 0 grand_customer_open_balance = 0 %> <% @shipments.each do |shipment| %>  <%= shipment.file_number %> <%= shipment.shipper.company_name %> <%= shipment.hbl %> <%= shipment.status %> <%= shipment.age %> <%= shipment.invoice.read_issued_at unless shipment.invoice.nil? %> <%= number_to_currency shipment.invoice.customer_total unless shipment.invoice.nil? %> <%= number_to_currency shipment.invoice.customer_amount_paid unless shipment.invoice.nil? %> <%= number_to_currency shipment.invoice.customer_open_balance unless shipment.invoice.nil? %>  <% grand_customer_total += shipment.invoice.customer_total grand_customer_amount_paid += shipment.invoice.customer_amount_paid grand_customer_open_balance += shipment.invoice.customer_open_balance %> <% if @shipments.last == shipment %>       Totals <%= number_to_currency grand_customer_total %> <%= number_to_currency grand_customer_amount_paid %> <%= number_to_currency grand_customer_open_balance %>  <% end %>