Rails - Ajax - Updating Nested Form in Partial

Question

I am trying to create a form that takes values from a table of input boxes. The user can enter the values in this table manually, or upload an excel spreadsheet. All of this works fine, but I want the user to be able to import a spreadsheet, and have the data table updated without reloading the page. The primary model to store this information is a DataTable object.

views/data_tables/index.html.erb looks like this:

<div id="tabs" class="tabs-bottom">
    <ul>
        <li><a href="#tabs-1">Data Input</a></li>
        <li><a href="#tabs-2">Data Display</a></li>
    </ul>
    <div class="tabs-spacer"></div>
    <div id="tabs-1" class="tab_frame">
        <%= render @data_table %>
    </div>
    <div id="tabs-2" class="tab_frame">
        <%= render "data_display" %>
    </div>
</div>

I am using a tabbed view from the Jquery-UI.

The partial, views/data_tables/_data_table.html.erb, looks something like this:

<%= nested_form_for @data_table, :remote => true do |f| %>
    <div id="table_pane">
    <table id="table_input" class="table_input">
        <tbody>
            <%= f.fields_for :financial_rows, :wrapper => false do |dr| %>
                <tr class="fields">
                    <td>
                        <%= dr.link_to_remove "x", {:class => "btn btn-danger"} %>
                    </td>
                    <td class="month">
                        <%= dr.text_field :month, :value => (dr.object.month.to_i) %>
                    </td>
                    <td class="year">
                        <%= dr.text_field :year, :value => (dr.object.year.to_i) %>
                    </td>
                   <td class="currency">
                       <% # . . .  %>
                       <% #Multiple fields omitted for brevity %>
                       <% # . . .  %>
                   </td>
               </tr>
            <% end %>
        </tbody>
    </table>
    <%= f.link_to_add "+", :financial_rows, :data => { :target => "#table_input" }, :class => "btn btn-success" %></br>
    </div>
    <%= f.submit :value => "Render Data" %>
<% end %>

<%= form_tag import_data_tables_path, multipart: true, remote: true do %>
    <%= file_field_tag :file %>
    <%= submit_tag "Import Spreadsheet" %>
<% end %>

The import form at the end is what I am having trouble with. In my controller, controllers/data_tables_controller.rb, my import method looks like this:

def import
    @data_table = DataTable.new
    if !params[:file].blank?
        imported_file = params[:file]
        spreadsheet = read_file(imported_file)
        header = spreadsheet.row(2)
        (3..spreadsheet.last_row).each do |i|
            data = Hash[[header, spreadsheet.row(i)].transpose]
            f_row = FinancialRow.new
            f_row.attributes = data.to_hash.slice(*FinancialRow.accessible_attributes)

            @data_table.financial_rows << f_row
        end
        respond_to do |format|
            format.html { redirect_to @data_table}
            format.js
            format.json { render json: @data_table, location: @data_table}
        end
        #render('index')
    else
        flash[:error] = "Select a file for import"
        @data_table.financial_rows.build
        #render('index')
    end
end

When I import a file without trying to use Ajax, the page reloads with the text fields of the data table fully populated, but when I try to use Ajax, the page just reloads without any updates to the data table. I have written a javascript file which theoretically should replace the div the datatable is in.

views/data_tables/import.js.erb contains:

$("#tabs-1").html("<%= escape_javascript(render(:partial => @data_table)).html_safe %>");

I've scoured stackoverflow for hours, reading posts on how to replace a rendered partial using Ajax, but I haven't found anything that has worked for me. I'm sure it is something simple I am overlooking, but I'm having a lot of trouble wrapping my head around how Ajax is implemented with Rails, and how and why one should use either format.html, format.js, or format.json.

I am using rails 3.2.12. Some noteworthy gems I am using is the 'nested_form' gem to handle the data_table form, and 'roo' to handle importing the spreadsheet.