Nested form for has_many through association - ruby

Question

I have two models, reservations and tables, with has_many through relationship between them with a join table and model collections, that has a separate attribute called :units_sold
my Reservation model:
class Reservation < ActiveRecord::Base
has_many :tables, through: :collections
has_many :collections
end
my table model:
class Table < ActiveRecord::Base
has_many :reservations, through: :collections
has_many :collections
end
and finally the collection model:
class Collection < ActiveRecord::Base
belongs_to :table
belongs_to :reservation
end
E.g:
A reservation in my name for 9 people (:units_sold) has 2 tables each with a capacity of 6 and I want 4 people in one table and 5 on the second table
What I have currently is this:
reservation_params
def reservation_params
params.require(:reservation).permit( :name, :total_units, table_ids: [],
collection_attributes: [ :units_sold],
table_attributes: [:capacity, :title])
end
and my form to submit a reservation:
<%= form_for [current_user, #account, #reservation] do |f| %>
<header>
<h1>Make your reservation</h1>
</header>
<%= f.text_field :name, placeholder: "Name" %>
<%= f.number_field :total_units, placeholder: "How many people..." %>
<%= f.fields_for :collections do |c|%>
<% #tables.each do |p| %>
<label for="<%= p.title %>"><%= p.title %></label>
<%= c.number_field :units_sold, placeholder: "People per table..." %>
<%= check_box_tag "reservation[table_ids][]", p.id %>
<% end %>
<% end %>
<%= f.submit "Save" %>
<% end %>
How should I do the reservation_params in the reservation controller? And nest the form to accept :units_sold for each table/reservation association

Answer 1

First, you should define the associations like :
has_many :collections
has_many :reservations, through: :collections
as in, first define collections and then reservations through collections. Similarly, update the associations in the Table model.
Then in the reservation model after defining the associations, add the following line:
accepts_nested_attributes_for :collections
In reservation_params, the key "collection_attributes" and "table_attributes" should be "collections_attributes" and "tables_attributes" respectively.