The popular CListView and CGridView widgets each take a data provider and iterate over each data object produced, calling the user's code to render each row one at a time, and most are familiar with the use of the $data variable to represent the current model object or array.
More or less I use auto-complete field for a form. CJuiAutoComplete is a yii widget for this purposes.
The common use case is to make an ajax request and retrieve a list from the database. So in this case you have to write a controller action to return you a json encoded list.
What if I had a generic action to do this work for me?