webform email field autocomplete

Question

I can quite easily add ajax autocomplete properties to a regular textfield using the code below, but it doesn't work when I change the field to type webform_email. Is it possible to do?

function flower_order_form_alter(&$form, &$form_state, $form_id) {
    if ($form_id == 'webform_client_form_68911') {
        //Add autocomplete fields for manager username
        $form['submitted']['name_of_authorising_manager']['#autocomplete_path'] = 'user/autocomplete';  
    }
}

Here's the dpr output for the relevant field in the form:

Array
(
    [#type] => webform_email
    [#title] => Name of authorising manager:
    [#title_display] => inline
    [#default_value] => 
    [#required] => 1
    [#weight] => 4
    [#description] => 
    [#attributes] => Array
        (
            [class] => Array
                (
                    [0] => email
                )

        )

    [#element_validate] => Array
        (
            [0] => _webform_validate_email
        )

    [#theme_wrappers] => Array
        (
            [0] => webform_element
        )

    [#translatable] => Array
        (
            [0] => title
            [1] => description
        )

    [#webform_component] => Array
        (
            [nid] => 68911
            [cid] => 18
            [pid] => 0
            [form_key] => name_of_authorising_manager
            [name] => Name of authorising manager:
            [type] => email
            [value] => 
            [extra] => Array
                (
                    [title_display] => inline
                    [private] => 0
                    [disabled] => 0
                    [unique] => 0
                    [width] => 
                    [description] => 
                    [attributes] => Array
                        (
                        )

                    [conditional_component] => 
                    [conditional_operator] => =
                    [conditional_values] => 
                )

            [mandatory] => 1
            [weight] => 4
            [page_num] => 1
        )

    [#webform_private] => 0
    [#validated] => 1
    [#webform_validated] => 
)

Answer 1

You can only use type of fields which are defined in hook_element_info.

List all the type of elements using drush by:

drush ev "print_r(array_keys(module_invoke_all('element_info')));"

If you don't need to use Webform email, check the Email field module how it's implementing such element type. See: Usage of email field with the form API.

Answer 2

As far as I can see, Webform module provides it's own form elements for email and some other kinds of data, and it simply does not implement autocomplete for them. You need to either implement hook_webform_component_info in your custom module to add this functionality, or fill a feature request on webform's issue queue.