Horde Config: How to fill dropdowns with application data with configspecial

Horde provides system wide customisation and configuration of applications through php configuration files. These files can be edited by hand or written from an administrator config UI. This ui is automatically generated from a file called conf.xml located in your $application/config/ directory.

The config xml allows dropdowns, multiselect fields, tick boxes, radio buttons and even conditionally adding or removing a field or inserting a valid php expression.

For example a  dropdown box in the horde base application’s config is generated by this snippet:

<configenum name="use_ssl" quote="false" desc="Determines how we generate
  full URLs (for location headers and such).">2
    <value desc="Assume that we are not using SSL and never generate https
    <value desc="Assume that we are using SSL and always generate https
    <value desc="Attempt to auto-detect, and generate URLs
    <value desc="Assume that we are not using SSL and generate https URLs only
    for login.">3</value>

This is all nice but what if you need to provide application data rather than static values? The answer is configspecial

    <configspecial application="turba" name="sources" />

How does that work?

<configspecial> calls the horde api. the “application” part tells you which application’s api to call. You can either reference an application by its registry name (horde, imp, kronolith, turba…) or by its api name (horde,mail, calendar, addressbook)

What’s the difference? When you call turba, you get turba. When you call addressbook, you can hook into whatever application provides addressbook. For example, spam handling and ticket queues have been implemented by multiple applications. You can even implement your own handlers for any existing api.

The called application must have a method configSpecialValues() in its lib/Application.php class file. This method gets called and its only parameter is the “name” property from the xml. In our example it’s “sources”. This method will return an array of source names to use in your config screen.

     * Returns values for <configspecial> configuration settings.
     * @param string $what  The configuration setting to return.
     * @return array  The values for the requested configuration setting.

    public function configSpecialValues($what)
        switch ($what) {
        case sources:
            try {
                $addressbooks = Turba::getAddressBooks(Horde_Perms::READ);
            } catch (Horde_Exception $e) {
                return array();
            foreach ($addressbooks as &$addressbook) {
                $addressbook = $addressbook['title'];

            $addressbooks[''] = _("None");
            return $addressbooks;

Et voila – you have a list of addressbooks to choose from.

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