Auto_complete_for not working

Rails
1

I have around one million customers in postgre table.

I want a select box in my form when I type characters (few),
the first 10 records should be displayed.

When I use auto_complete_for in controller, I get the following
error message:

undefined method `auto_complete_for’ for #AdminController:0x37a3318

2

Check out the source at http://demo.script.aculo.us/ajax/autocompleter,
it gives a pretty good example. Also, make sure your fields don’t have
reserved names. I know I had a problem with a field named “description”
so I assume that was a reserved word. I changed it to desc and had no
problem.