rails build method for complex model with days of the week

Question

I have a set of nested models for storing prices for individual rooms.

Ie.

  Places
    Rooms
      Room_rates

Each model has the necessary accepts_nested_attributes_for and has_many belongs_to association and I have a form and a build method which works perfectly for the initial creation.

My question is how to make a smarter controller, that either builds the field if it doesn't exist, or reads from it if it does (and doesn't build it). Currently it only works for the initial input, otherwise it attempts to build more fields than are possible and breaks on resubmission.

  def new
    @place = Place.find(params[:place_id])
    @rooms = @place.rooms

    @rooms.each do |r|
      7.times { r.room_rates.build } #days of the week
    end

  end

tried

@rooms.each do |r|
  7.times { 
    unless r.room_rates
      r.room_rates.build
    end 
  }
end

database for room_rates

id, room_id, dayofweek, price

form

<% form_for @place do |f| %>
  <%= f.error_messages %>


<table>
  <tr>  
    <th>Room</th>
    <th>Mon</th>
    <th>Tue</th>
    <th>Wed</th>
    <th>Thu</th>
    <th>Fri</th>
    <th>Sat</th>
    <th>Sun</th>
  </tr>
  <% f.fields_for :rooms do |room| %>
    <% dow = 0 %>
      <tr>
        <td><%= room.text_field :name %></td>

        <% room.fields_for :room_rates do |rates| %>

            <td>    
                <%= rates.text_field :price %>
                <%= rates.text_field :dayofweek, :value => dow %>   
            </td>
            <% dow += 1 %>
        <% end %>
      </tr>
  <% end %>
</table>

<%= f.submit "Submit" %>

<% end %>

Answer 1

You can try:

@rooms.each do |r|
  ((r.room_rates.size+1)..7).each {   
      r.room_rates.build       
  }
end