Template error - ajax in rails 3 - ruby-on-rails

Question

I have a nav menu with 2 tabs/links in the show.html.erb file, in UsersController.rb, I would like to use ajax to render different partial for the tabs.
In the show.html.erb I have a div named profile-data where I want to show the content.
So I do something like this:
The link structure:
<li><%= link_to "College friends", college_friends_path, :remote => true %></li>
<li><%= link_to "Highschool friends", highschool_friends_path, :remote => true %></li>
I define the routes:
match "college_friends" => "users#college_friends", :as => "college_friends"
match "highschool_friends" => "users#highschool_friends, :as => "highschool_friends"
And I define in my UserController.rb the necessary methods:
class UsersController < ApplicationController
def show
#user = User.find(params[:id])
end
def college_friends
respond_to do |format|
format.js
end
end
def highschool_friends
respond_to do |format|
format.js
end
end
end
Last thing we have the JS files:
*college_friends.js.erb*
$('#profile-data').html("<%= escape_javascript(render(:partial => 'college_friends')) %>");
*highschool_friends.js.erb*
$('#profile-data').html("<%= escape_javascript(render(:partial => 'highschool_friends')) %>");
The partial code: _college_friends.html.erb
<% groups = #user.friends.group_by(&:college_name) %>
<% sorted_groups = groups.sort_by{|key, values| values.count}.reverse %>
<% sorted_groups.each do |collegename, friends| %>
<% next if collegename.blank? %>
<div class="contentbox">
<div class="box-header">
<h3><%= collegename %></h3>
<div class="meta-info">
<p><i class="icon-map-marker"></i> Malmö</p>
<p><i class="icon-user"></i><span class="count"> <%= friends.count %></span> vänner</p>
</div>
</div>
<ul class="friends-list">
<% friends.map do |friend| %>
<li><%= image_tag(friend.image) %>
<% end %>
</ul>
</div>
<% end %>
Nothing happens when I click the the links, and get this error in the console:
Started GET "/universitet_friends" for 127.0.0.1 at 2012-07-29 01:53:39 +0200
Processing by UsersController#universitet_friends as JS
Rendered users/_universitet_friends.html.erb (1.6ms)
Rendered users/universitet_friends.js.erb (3.1ms)
Completed 500 Internal Server Error in 7ms
ActionView::Template::Error (undefined method `friends' for nil:NilClass):
1: <% groups = #user.friends.group_by(&:college_name) %>
2: <% sorted_groups = groups.sort_by{|key, values| values.count}.reverse %>
3: <% sorted_groups.each do |collegename, friends| %>
4: <% next if collegename.blank? %>
app/views/users/_universitet_friends.html.erb:1:in `_app_views_users__universitet_friends_html_erb___1983680250475155079_70236040373720'
app/views/users/universitet_friends.js.erb:1:in `_app_views_users_universitet_friends_js_erb__1317362850668628869_70236044930260'
app/controllers/users_controller.rb:19:in `universitet_friends
Any help would be appreciated.

Answer 1

ActionView::Template::Error (undefined method `friends' for
nil:NilClass):
This is telling you that your #user variable is nil. This happened because when you went back to your controller for the AJAX request, you never actually set the #user variable. It does not persist between requests. You need to pass that variable during the ajax request. One way to do it is to add a user_id param to the ajax URL.

Answer 2

May be you can do something like this too
<%=link_to "Highschool friends", college_friends_path(:user_id => #user.id), :remote => true %>
The best way to do however would be to pass the user_id param to ajax url..you can fire the ajax request on link "on-click" event.