function log(message) {
        $( "<div/>" ).text( message ).prependTo("#log");
    }

   $("#managers").autocomplete({
        source : function(request, response) {
            $.ajax({
                url : "/managerlist",
                dataType : "json",
                data : {
                    style : "full",
                    maxRows : 12,
                    term : request.term
                },
                success : function(data) {
                    var results = [];
                    $.each(data, function(i, item) {
                        var itemToAdd = {
                            value : item,
                            label : item
                        };
                        results.push(itemToAdd);
                    });
                    return response(results);
                }
            });
        }
    });

def manager_list
  list=Project.all.map{|i|i.manager_user_id}
  arr= [].concat(list.sort{|a,b| a[0]<=>b[0]}).to_json
  render :json =>arr
end

match '/managerlist' => 'projects#manager_user_id'

<p>
        <%= f.label :manager_user_id %><br />
        <input id="managers" />
    </p>

def manager_list
  list=Project.all.map{|i|i.manager_user_id}
  arr= [].concat(list.sort{|a,b| a[0]<=>b[0]}).to_json
  render :json =>arr
end

return response(JSON.stringify({ results: results }));

$("#managers").autocomplete({
    minLength: 2,   // 2 or whatever you want
   // rest of your code