How can I pass the parameters to controller correctly? - ruby-on-rails

Question

From show view: I'd like to pass the shown message's id to discard action and trash the message.
From index view: I'd like to pass the checked messages' ids to discard action and trash them all at once.
But I only can trash one record at once even if I check multiple and submit from index view.
How can I archive both 1 and 2 with the same action????
Routes
match 'messages/discard(/:id)' => 'messages#discard', :via => :post , :as => :discard_messages
index view
<%= form_tag(:action => discard, :via => 'post') do %>
<% #messages.each do |m| %>
<tr>
<td><%= check_box_tag "id",m.id %></td>
<td><%= m.last_message.id %></td>
<td><%= 'unread' if m.is_unread?(current_user) %></td>
<td><%= m.last_message.created_at.to_s(:jp) %></td>
<td><%= m.last_sender.username %></td>
<td><%= link_to m.subject, show_messages_path(:id => m, :breadcrumb => #box) %></td>
</tr>
<% end %>
<%= submit_tag "discard", :class => 'btn' %>
<% end %>
show view
<%= link_to 'Discard', discard_messages_path(#messages), :class => 'btn', :method => 'post' %>
controller
def discard
conversation = Conversation.find_all_by_id(params[:id])
if conversation
current_user.trash(conversation)
flash[:notice] = "Message sent to trash."
else
conversations = Conversation.find(params[:conversations])
conversations.each { |c| current_user.trash(c) }
flash[:notice] = "Messages sent to trash."
end
redirect_to :back
end

Answer 1

use the [] naming in your html, which rails will then make available as an array in the params
index.html.erb
<td><%= check_box_tag "message_id[]", m.id %></td>
controller
# ...
else
conversations = Conversation.where("id IN (?)", params[:message_id][])
# ...
to simplify things further I would remove the conditional in your action and create two separate actions
routes
resource :messages do
member do
post 'discard' # /messages/:id/discard
end
collection do
post 'discard_all' # /messages/discard_all?message_id[]=1&message_id[]=22
end
end