Creating Rails objects using same form - ruby-on-rails

Question

I am building an application to manage debts and am trying to create three objects using the same form.
The models are;
Debt (the amount owed)
class Debt < ActiveRecord::Base
belongs_to :user
belongs_to :creditor
belongs_to :debtor
accepts_nested_attributes_for :debtor, :creditor
end
Debtor (The person who owes)
class Debtor < ActiveRecord::Base
belongs_to :user
has_many :debts
end
Creditor (The person who is owed)
class Creditor < ActiveRecord::Base
belongs_to :user
has_many :debts
end
I am using the new debt form and would like to show fields for debtor and creditor. So when a new debt is created, so is the associated debtor and creditor.
I have viewed the documentation however, cannot get the fields for debtor or creditor to display on the form.
This is the form
<%= simple_form_for(#debt) do |f| %>
<%= f.error_notification %>
<!-- Debt fields -->
<div class="form-inputs">
<%= f.association :user %>
<%= f.input :amount %>
<%= f.input :commission %>
<%= f.input :invoice_issued %>
<%= f.input :invoice_date %>
<%= f.input :status %>
<%= f.input :details %>
</div>
<!-- Debtor Fields -->
<ul>
<%= f.fields_for :debtor do |debtor_form| %>
<li>
<%= debtor_form.association :user %>
<%= debtor_form.input :business_name %>
<%= debtor_form.input :abn %>
<%= debtor_form.input :first_name %>
<%= debtor_form.input :last_name %>
<%= debtor_form.input :email %>
<%= debtor_form.input :mobile_number %>
<%= debtor_form.input :phone_number %>
</li>
<% end %>
</ul>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
Any help is appreciated.
EDIT
create_table "debts", force: :cascade do |t|
t.integer "user_id"
t.float "amount"
t.float "commission"
t.boolean "invoice_issued"
t.date "invoice_date"
t.string "status"
t.text "details"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end

Answer 1

You need to build your debt's debtor or creditor in your controller:
#controller
def new
#debt = Debt.new
#debt.build_debtor
#bebt.build_creditor
end