Rails - how to save options chosen by user - ruby-on-rails

Question

I have two models: Meal and Tag. They are associated by HABTM. What I want to do is to add new meal. So I have new.html where is name field, preparation field, and all tags (represented by toggle-buttons - every tag has own toggle-button). User can clicked tags, which want to save in this meal.
And here is a problem. I can display all tags, but I have no idea how can I tell rails to save only clicked tags.
Could you help me find right approach?
oh, and there is a user too (user has many meals), but I thing it doesn't matter.
Here is my view:
<%= form_for(#meal,:html => {:class => "meal-data-form"}) do |f| %>
<%= render 'shared/error_messages', object: f.object%>
<%= f.label :name, "Nazwa *" %>
<%= f.text_field :name, class: 'form-control'%>
<%= f.label :preparation, "Sposób przyrządzenia" %>
<%= f.text_area :preparation, class: 'form-control' %>
<h3>Określ tagi dla tego posiłku</h3>
<div id="tags-associated-with-meal">
<h4>Rodzaj posiłku</h4>
<div id="associated-nutrient-tags">
<% current_user.nutrient_tags.each do |nutrient_tag| %>
<button id="associated-type-tag-<%= nutrient_tag.id %>" type="button" class="btn btn-primary" data-toggle="button" aria-pressed="false" autocomplete="off">
<%= nutrient_tag.name %>
</button>
<% end %>
</div>
</div>
<%= f.submit yield(:button_name), class: "btn btn-primary" %>

Answer 1

I would not use a toggle button to do this, I would probably use checkboxes.
This is what you would do if you used checkboxes:
<%= f.collection_check_boxes :nutrient_tags_ids, current_user.nutrient_tags, :id, :name do |b| %>
<div class="collection-check-box">
<%= b.check_box %>
<%= b.label %>
</div>
Here is something for reference: http://www.sitepoint.com/save-multiple-checkbox-values-database-rails/
And here is the Rails collection_check_boxes official documentation: http://apidock.com/rails/v4.0.2/ActionView/Helpers/FormOptionsHelper/collection_check_boxes
Hope that helps.