Rails5分组，总和并显示在视图中-Rails5groupby,sumandshowinview

so how can i get sales group by category and sum the total of sales in each category? and how can i show it in my view (in a instance variable). For example i want to show in my view this:

那么我如何才能按类别获得销售组并总计每个类别的销售总额?以及如何在我的视图中显示它(在实例变量中)。例如,我想在我的视图中显示:

CategoryOne : Total $3000 (maybe the result is a hash but how can i show it in the view?

CategoryOne:总计$ 3000(可能结果是哈希,但我怎么能在视图中显示它?

CategoryTwo : Total $4000

CategoryTwo:总计4000美元

CategoryThree : Total $2200

类别3:总计2200美元

and so on....

等等....

which is the right rails way query (active record)? and how to show the results in view? thanks

这是正确的rails方式查询(活动记录)?以及如何在视图中显示结果?谢谢

2 个解决方案

category = Category.last
category.sales.sum(:total)

# app/models/category.rb
class Category 

# app/controllers/categories_controller.rb
@categories = Category.includes(:sales)

<% @categories.each do |c| %>
  <%= "Category #{c.name}: Total $#{c.sales_total} %>
<% end %>

def sales_total_on(date)
  sales.where(date: date).sum(:total)
end