Question

I have a Donation.rb model with an amount column that takes an integer. I want to sum all the individual donations together and show the total on the home page.

In the home_controller, I’m doing @donations = Donation.all and then in the view I do

<% sum = 0 %>
<% @donations.each do |donation| %> 
<%= sum += donation.amount if donation.amount? %>
<% end %>

The problem is that this is printing the running sum each time a new donation is added to it. I just want the total sum at the end after they’ve all been added together.

Answer 1

You’re getting running sum printed, because you’re actually printing it with the = sign.
You need to change this line:

<%= sum += donation.amount if donation.amount? %>

With:

<% sum += donation.amount if donation.amount? %>

And then, just print the value of sum wherever you want doing:

<%= sum %>