app/views/products/_form.html.erb
<%= simple_form_for(@product, url: @product.new_record? ? products_path : product_path(@product), html: {class: 'form-horizontal'}, wrapper: :horizontal_form) do |f| %>
<%= render partial: 'shared/form/error_messages', locals: { resource: @product } %>
<%= f.input :name %>
<%= f.input :text, as: :text, input_html: {style: 'width: 500px; height:300px;'} %>
<div class="form-group string required">
<label class="string required control-label col-sm-3 control-label">
<abbr title="required">*</abbr> <%= t('areas.index.title') %>
</label>
<div class="col-sm-9">
<% Area.all.each do |area| %>
<label class="checkbox">
<input class="check_boxes required" id="product_area_ids_<%=area.id%>" name="product[area_ids][]"
type="checkbox" value="<%=area.id%>"<%= @product.area_ids.include?(area.id) ? ' checked="checked"' : '' %>/>
<%= link_to area.name, area %>
</label>
<% end %>
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-3 col-sm-9">
<%= f.button :submit %>
</div>
</div>
<% end %>