Rails: using fields_for with check_box

Question

I have a site that shows upcoming events. Event has a boolean property called :approved. I want to display a list of all the events for an admin and checkboxes for the :approved field. They should be checked if approved and unchecked otherwise. I'm guessing I need to use fields_for? When the admin checks an :approved field in the form I want it to transmit inside params as '1' or 'true' or 'checked' and the opposite when he unchecks the field and submits the form. I also need the name of each field in the params list to be something like events[event.id] but what I have comes up as events[event.id][approved] and none of my checkboxes are checked. Here's what I have so far:

admin_index.html.erb

<%= form_tag '/admin_events', method: :get do %>
  <table id="admin_events_table" class="table-striped" style="width: 100%">
    <thead>
      <th>Date</th>
      <th>Time</th>
      <th>Title</th>
      <th>Venue</th>
      <th>Visibility</th>
      <th></th>
      <th></th>
    </thead>
    <tbody id="admin_events">
      <%= render @events %>
    </tbody>
  </table>
  <%= submit_tag "Approve", class: "btn btn-default" %>
<% end %>

_event.html.erb

<tr>
  <td><%= fields_for "events[#{event.id}]" do |form| %>
        <%= form.check_box :approved %>
      <% end %>
  </td>

<td><%= event.date.strftime('%A %B %-d') %></td>
<td><%= event.time.strftime('%l:%M %P') %></td>
<td><%= event.title %></td>
<td><%= Venue.find(event.venue_id).name %></td>
<td><%= link_to "Edit", edit_event_path(event) %></td>
<td><%= link_to "Delete", event, method: :delete, data: { confirm: "Are you sure?" } %></td>

UPDATE here's what I came up with in my controller in order for the app to update :approved to either true or false. But it seems too complicated:

events_controller.rb

if params[:commit]
  ids = params[:events].keys
  values = params[:events].values
  ids.each_with_index do |id, i|
    event = Event.find(id)
    if values[i].values[0] == "0"
      event.update(approved: false)
    else
      event.update(approved: true)
    end
  end
  redirect_to admin_events_path
end

Answer 1

If your view looks like this:

<%= fields_for "events[]", event do |form| %>
  <%= form.check_box :approved %>
<% end %>

then your params should contain a hash that looks like this (let's say event with id 29 is checked and event with id 23 is unchecked):

"events" => {"29" => {"approved" => "1"}, "23" => {"approved" => "0"}}

and your controller can save them like this:

events = params[:events]
events.each do |id, attrs|
  event = Event.find(id)
  event.update_attributes(attrs)
end

redirect_to admin_events_path