app/views/products/_import_modal.html.erb
<div class='modal-dialog'>
<div class='modal-content'>
<div class='modal-body'>
<%= form_tag import_products_path, multipart: true, remote: true do %>
<div class="form-group">
<%= label_tag :file %>
<%= file_field_tag :file, class: "form-control" %>
</div>
<div>
<%= submit_tag "Submit", class: "btn btn-primary"%>
</div>
<% end %>
</div>
</div>