Question

或许是一个非常容易的解决办法,但试图说明如何找到属于以下各栏的积级:

@milestones = Milestone.where(:buyer_id => current_user.id).where(:status =>  Paid )

I tried <%= @milestones.amount.inject(:+) %> in the view, didn t work.

Answer 1

当然,它没有工作。没有关于<条码>的<条码>amount。为此:

@milestones.map(&:amount).inject(:+)

Answer 2

Given:

@milestones = Milestone.where( :buyer_id => current_user.id ).
                        where( :status   =>  Paid  )

然后......

<%= @milestones.sum :amount %>

或者说:

@milestones_sum = Milestone.where( :buyer_id => current_user.id,
                                   :status   =>  Paid 
                                 ).
                            sum( :amount )

......

<%= @milestones_sum %>

Answer 3

<0>@milestones没有amount。这种方法不使用<代码>Milestone——其编号为<>ActiveRecord:Relation或Array。

您可尝试@milestones.map(&:amount).inject(+),以收集和汇总铁路应用中的所有数量。

Or you can use @milestones.sum(:amount) to have ActiveRecord perform the calculation in the database for you, which could be much faster / efficient. Other calculations are also available in ActiveRecord::Calculations::ClassMethods.

友情链接