autocomplete enhancements

(Ok, I am just editing this a little bit to point out the fact that this was initially reported for version 6.x, but is )

This patch fixes one minor bug in autocomplete.js and adds a little functionality. The addition of functionality doesn't break any prior behavior or code.

The bug:
The original behavior attach function takes a "context" parameter, but doesn't use it.

Description of the new functionality:

Assume we have an id and a name form element, i.e.

        $form['id'] = array(
                '#type' => 'textfield',
                '#title' => t('Id'),
                '#required' => true,
                '#default_value' => $custdata['sid'],
                '#autocomplete_path' => 'somepath/id-lookup';
                '#size' => 11
        );
        $form['name'] = array(
                '#type' => 'textfield',
                '#title' => t('Name'),
                '#required' => true,
                '#size' => 30,
                '#attributes' => array('class'=>array('autocomplete-id')),
        );

Note the attribute for name element. It hooks the name element with autocomplete select handler for the id element. I.e. when the id element gets populated with a value from the autocomplete lookup, the name element is auto populated with the associated name value for the id value.

The autocomplete lookup function can return whole records, using the simple rule that the returned keys are potential values for the main-lookup field, while individual fields from the records map to form elements with the same name (provided they have their class set to 'autocomplete-
'

An example autocomplete lookup function for the above case could be:

function somelookup($id) {
     $data = get_custdata_by_id($id);
     $values = array();
     foreach ($data as $cust) {
        $mapped = array();
        $mapped['id'] = $cust['identification_number'];
        $mapped['name'] = $cust['name'];
        $values[$cust['identification_number']] = $mapped;
     }       
     drupal_json_output($values);
}

Another change is also in the jsAC function. The change consists in forcing the select function (and hence the autopopulation of associated elements) to trigger if the user enters a value exisiting in the "drop-down" list without actually selecting/highlighting it. The only thing that remains to be considered for that (and it is simply a question of selecting an appropriate timeout) is to handle the case when the user enter the value "too-fast".

I've been using this for quite some time now and found it very useful.

(Note in the select handler there is also a check for if the element has the attribute "stripid". This is a special case I use in dynamic tables, i.e. tables where users can add new rows to an input form. In that case I can have form elements like id1, id2,... name1, name2,... so when pairing the name attributes with their corresponding id values, I need to strip the id from the name in order to match it in the returned record.)