Rails has many through not working - ruby-on-rails

Question

I've got 3 models:
Vacancy
has_many :address_vacancies
has_many :addresses, through: :address_vacancies
Address
has_many :address_vacancies
has_many :vacancies, through: :address_vacancies
AddressVacancy
belongs_to :address
belongs_to :vacancy
and in my form I use the following code:
<%= f.collection_select :address_id, Address.order("CREATED_AT DESC"),:id,:title, include_blank: true %>
which throws an error: undefined method address_id', why is that and what am I doing wrong?
Edit
The full form looks like this:
<%= form_for(#vacancy) do |f| %>
<% if #vacancy.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#vacancy.errors.count, "error") %> prohibited this vacancy from being saved:</h2>
<ul>
<% #vacancy.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :title %><br>
<%= f.text_field :title %>
</div>
<div class="field">
<%= f.label :address %>
<%= f.collection_select :address, Address.order("CREATED_AT DESC"),:id,:title, include_blank: true %>
</div>
<div class="field">
<%= f.label :signup_until %><br>
<%= f.date_select :signup_until %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>

Answer 1

This:
<div class="field">
<%= f.label :address %>
<%= f.collection_select :address, Address.order("CREATED_AT DESC"),:id,:title, include_blank: true %>
</div>
Isn't valid in the context of a Vacancy form (from the form_for #vacancy) since a Vacancy doesn't have a single address attribute. It has a collection of addresses through the has_many association. It would also be invalid to use :address_id for the same reason.
If you want to edit the various addresses for the one vacancy, you would need a subform. You'd use accepts_nested_attributes_for in the model, and fields_for in the view.
<%= form_for #vacancy do |f| %>
...
<%= f.fields_for :addresses do |af| %>
...
<!-- Here you'd render a partial or a set of inputs for this address %>
<%= af.input :street %> <!-- e.g., if there's a street attribute for Address -->
...
<% end %>
...
<% end %>