rails complex form simple_fields_for without loop | cocoon, simple_form |

Question

I have a kind of complex form to build. I am using cocoon and simple-form for building it. In that application there are contracts and for every contract a user should be able to create multiple distributions of a certain type via that form.

My model structure looks like the following (just so you can imagine it):

class Contract < ApplicationRecord
  has_many distributions
  accepts_nested_attributes_for :distributions
end

class Distribution
  belongs_to :contract
  #  distribution_type :string // e.g. month or city
  #  percentage
  #  value
end

What I want to achieve is to let the user choose a distribution_type via a dropdown that lies inside the "_distribution_fields.html.erb" partial. If a user selects a certain type, for example "month", the predefined 'div' is loaded via javascript and builds multiple fields at once as follows:

<div class="nested-fields">
  <div class="row">
    <div class="row">
      <%= f.input :distribution_type, wrapper_html: {class: 'col-xs-6 col-md-2'}, input_html: {data: {'toggle-select': 'distribution-type-0'}, class: 'distribution_type_select'}, required: true, disabled: @readonly %>
    </div>

    <div class="row">
  <div id="distribution-type-0-event_type" class="distribution-type-selection">
      <%= hidden_field_tag 'event_type', false, class: 'distribution_type_hidden_event_type' %>
      <% @contract.event_types.each do |event_type| %>
            <div class="col-xs-6 col-md-4">
              <div class="field">
                <%= f.input :distribution_type, as: 'hidden', input_html: { class: 'event_type_distribution_hidden', value: 'event_type' } %>
                <%= f.input :value, input_html: { readonly: true, value: event_type } %>
                <%= f.input :percentage, required: true, disabled: @readonly %>
              </div>
            </div>
      <% end %>
  </div>
</div>

<div class="row">
  <div id="distribution-type-0-month" class="distribution-type-selection">
    <%= hidden_field_tag 'month', false, class: 'distribution_type_hidden_month' %>
    <% @contract.month_date_list.each do |month| %>
            <div class="col-xs-6 col-md-4">
              <div class="field">
                <%= f.input :distribution_type, as: 'hidden', input_html: { class: 'month_distribution_hidden', value: 'month' } %>
                <%= f.input :value, input_html: { readonly: true, value: month } %>
                <%= f.input :percentage, required: true, disabled: @readonly %>
              </div>
            </div>
    <% end %>
  </div>
</div>

<div class="row">
  <div id="distribution-type-0-city" class="distribution-type-selection">
    <%= hidden_field_tag 'city', false, class: 'distribution_type_hidden_city' %>
    <% @contract.location_cities.each do |city| %>
            <div class="col-xs-6 col-md-4">
              <div class="field">
                <%= f.input :distribution_type, as: 'hidden', input_html: { class: 'city_distribution_hidden', value: 'city' } %>
                <%= f.input :value, input_html: { readonly: true, value: city } %>
                <%= f.input :percentage, required: true, disabled: @readonly %>
              </div>
            </div>
    <% end %>
  </div>
</div>

<div class="col-xs-6 col-md-1">
  <div class="row">
    <div class="col-xs-12">
      <%= link_to_remove_association f, class: 'btn btn-danger delete-btn', disabled: @readonly, data: { confirm: 'You are about to delete the internet as well as to remove this kpi distribution? Are you sure?' }  do %>
          <i class="fa fa-trash"></i>
      <% end %>
    </div>
  </div>
</div>

In the surrounding "_form.html.erb" it is as follows:

...
    <%= field_set_tag 'KPI Distribution' do %>
                  <%= f.simple_fields_for :distributions do |distribution| %>
                      <%= render 'distribution_fields', f: distribution %>
                  <% end %>
                  <div class="links m-b-md">
                    <div class="text-left">
                      <%= link_to_add_association f, :kpi_distributions, class: 'btn btn-info btn-sm', disabled: @readonly do %>
                          <i class="fa fa-plus"></i>
                      <% end %>
                    </div>
                  </div>
              <% end %>
...

As you might have already recognized in the above part, there is a "simple_fields_for" instruction looping the "_distribution_fields" partial. Usually only a single field including all its inputs is created inside such an partial, but I want to set multiple at once. Is there a certain way for doing something like this? Are there any best practices to achieve such a thing? Or can I set the ids produced by cocoon manually?

best regards