Question

I have a User.rb model and a Donation.rb model. User.rb has_one :donation, and Donation.rb belongs_to :user.

I created a form whereby a donation gets linked to a user. In the console, I’m able to do this

ruby-1.9.2-p290 :003 > user.donation.amount
 => 1 

Similarily, I’m able to do this on the views/users/show.html.erb

<p>Donation:<%= @user.donation.amount if @user.donation.amount? %></p>

However, in views/home/index.html.erb, I’m doing this

<h3>Home</h3>
<% @users.each do |user| %>
  <p>User: <%=link_to user.name, user %></p>
  <p>Email: <%= user.email if user.email %></p>
  <p>Name:<%= user.name %></p>
  <p>Donation:<%= user.donation.amount if user.donation.amount? %></p>

and getting this error

    NoMethodError in Home#index

Showing /Users/michaeljohnmitchell/Sites/leafpledge/app/views/home/index.html.erb where line #6 raised:

undefined method `amount?' for nil:NilClass

I’m assuming this is because the association between User.rb and Donation.rb doesn’t work with the index action in the home_controller.rb because every user is being fetched rather than the particular user that I have in the views/users/show.html.erb.

 def index
    @users = User.all
  end

Any idea how I can get it to work?

Answer 1

Your if check should be checking if the donation exists, not if the amount exists:

<p>Donation:<%= user.donation.amount if user.donation %></p>

Or, you could use the try method which will avoid the undefined method error if donation is nil:

<p>Donation:<%= user.donation.try(:amount) %></p>