Friendica Addon/Plugin development

Please see the sample addon 'randplace' for a working example of using some of these features.
Addons work by intercepting event hooks - which must be registered.
Modules work by intercepting specific page requests (by URL path).

Plugin names cannot contain spaces or other punctuation and are used as filenames and function names.
You may supply a "friendly" name within the comment block.
Each addon must contain both an install and an uninstall function based on the addon/plugin name.
For instance "plugin1name_install()".
These two functions take no arguments and are usually responsible for registering (and unregistering) event hooks that your plugin will require.
The install and uninstall functions will also be called (i.e. re-installed) if the plugin changes after installation.
Therefore your uninstall should not destroy data and install should consider that data may already exist.
Future extensions may provide for "setup" amd "remove".

Plugins should contain a comment block with the four following parameters:

 * Name: My Great Plugin
 * Description: This is what my plugin does. It's really cool.
 * Version: 1.0
 * Author: John Q. Public <>

Register your plugin hooks during installation.

register_hook($hookname, $file, $function);

$hookname is a string and corresponds to a known Friendica hook.

$file is a pathname relative to the top-level Friendica directory.
This should be 'addon/plugin_name/plugin_name.php' in most cases.

$function is a string and is the name of the function which will be executed when the hook is called.


Your hook callback functions will be called with at least one and possibly two arguments

function myhook_function(App $a, &$b) {


If you wish to make changes to the calling data, you must declare them as reference variables (with '&') during function declaration.


$a is the Friendica 'App' class.
It contains a wealth of information about the current state of Friendica:

It is recommeded you call this '$a' to match its usage elsewhere.


$b can be called anything you like.
This is information specific to the hook currently being processed, and generally contains information that is being immediately processed or acted on that you can use, display, or alter.
Remember to declare it with '&' if you wish to alter it.


Plugins/addons may also act as "modules" and intercept all page requests for a given URL path.
In order for a plugin to act as a module it needs to define a function "plugin_name_module()" which takes no arguments and needs not do anything.

If this function exists, you will now receive all page requests for "" - with any number of URL components as additional arguments.
These are parsed into an array $a->argv, with a corresponding $a->argc indicating the number of URL components.
So would look for a module named "plugin" and pass its module functions the $a App structure (which is available to many components).
This will include:

$a->argc = 3
$a->argv = array(0 => 'plugin', 1 => 'arg1', 2 => 'arg2');

Your module functions will often contain the function plugin_name_content(App $a), which defines and returns the page body content.
They may also contain plugin_name_post(App $a) which is called before the _content function and typically handles the results of POST forms.
You may also have plugin_name_init(App $a) which is called very early on and often does module initialisation.


If your plugin needs some template, you can use the Friendica template system.
Friendica uses smarty3 as a template engine.

Put your tpl files in the templates/ subfolder of your plugin.

In your code, like in the function plugin_name_content(), load the template file and execute it passing needed values:

# load template file. first argument is the template name,
# second is the plugin path relative to friendica top folder
$tpl = get_markup_template('mytemplate.tpl', 'addon/plugin_name/');

# apply template. first argument is the loaded template,
# second an array of 'name'=>'values' to pass to template
$output = replace_macros($tpl,array(
    'title' => 'My beautiful plugin',

See also the wiki page Quick Template Guide.

Current hooks


'authenticate' is called when a user attempts to login.
$b is an array containing:

'username' => the supplied username
'password' => the supplied password
'authenticated' => set this to non-zero to authenticate the user.
'user_record' => successful authentication must also return a valid user record from the database


'logged_in' is called after a user has successfully logged in.
$b contains the $a->user array.


'display_item' is called when formatting a post for display.
$b is an array:

'item' => The item (array) details pulled from the database
'output' => the (string) HTML representation of this item prior to adding it to the page










'profile_edit' is called prior to output of profile edit page.
$b is an array containing:

'profile' => profile (array) record from the database
'entry' => the (string) HTML of the generated entry



'directory_item' is called from the Directory page when formatting an item for display.
$b is an array:

'contact' => contact (array) record for the person from the database
'entry' => the (string) HTML of the generated entry



'profile_sidebar is called when generating the sidebar "short" profile for a page.
$b is an array:

'profile' => profile (array) record for the person from the database
'entry' => the (string) HTML of the generated entry


is called when formatting the block of contacts/friends on a profile sidebar has completed.
$b is an array:

'contacts' => array of contacts
'output' => the (string) generated HTML of the contact block





'personal_xrd' is called prior to output of personal XRD file.
$b is an array:

'user' => the user record for the person
'xml' => the complete XML to be output



is called when editing contact details on an individual from the Contacts page.
$b is an array:

'contact' => contact record (array) of target contact
'output' => the (string) generated HTML of the contact edit page





'avatar_lookup' is called when looking up the avatar.
$b is an array:

'size' => the size of the avatar that will be looked up
'email' => email to look up the avatar for
'url' => the (string) generated URL of the avatar


'emailer_send_prepare' called from Emailer::send() before building the mime message.
$b is an array, params to Emailer::send()

'fromName' => name of the sender
'fromEmail' => email fo the sender
'replyTo' => replyTo address to direct responses
'toEmail' => destination email address
'messageSubject' => subject of the message
'htmlVersion' => html version of the message
'textVersion' => text only version of the message
'additionalMailHeader' => additions to the smtp mail header


is called before calling PHP's mail().
$b is an array, params to mail()



is called after the navigational menu is build in include/nav.php.
$b is an array containing $nav from nav.php.


is called before vars are passed to the template engine to render the page.
The registered function can add,change or remove variables passed to template.
$b is an array with:

'template' => filename of template
'vars' => array of vars passed to template


is called after the other queries have passed.
The registered function can add, change or remove the acl_lookup() variables.

'results' => array of the acl_lookup() vars

Complete list of hook callbacks

Here is a complete list of all hook callbacks with file locations (as of 14-Feb-2012). Please see the source for details of any hooks not documented above.

boot.php: call_hooks('login_hook',$o);

boot.php: call_hooks('profile_sidebar_enter', $profile);

boot.php: call_hooks('profile_sidebar', $arr);

boot.php: call_hooks("proc_run", $arr);

include/contact_selectors.php: call_hooks('network_to_name', $nets);

include/api.php: call_hooks('logged_in', $a->user);

include/api.php: call_hooks('logged_in', $a->user);

include/queue.php: call_hooks('queue_predeliver', $a, $r);

include/queue.php: call_hooks('queue_deliver', $a, $params);

include/text.php: call_hooks('contact_block_end', $arr);

include/text.php: call_hooks('smilie', $s);

include/text.php: call_hooks('prepare_body_init', $item);

include/text.php: call_hooks('prepare_body', $prep_arr);

include/text.php: call_hooks('prepare_body_final', $prep_arr);

include/nav.php: call_hooks('page_header', $a->page['nav']);

include/auth.php: call_hooks('authenticate', $addon_auth);

include/bbcode.php: call_hooks('bbcode',$Text);

include/oauth.php: call_hooks('logged_in', $a->user);

include/acl_selectors.php: call_hooks($a->module . 'pre' . $selname, $arr);

include/acl_selectors.php: call_hooks($a->module . 'post' . $selname, $o);

include/acl_selectors.php: call_hooks('contact_select_options', $x);

include/acl_selectors.php: call_hooks($a->module . 'pre' . $selname, $arr);

include/acl_selectors.php: call_hooks($a->module . 'post' . $selname, $o);

include/acl_selectors.php: call_hooks($a->module . 'pre' . $selname, $arr);

include/acl_selectors.php: call_hooks($a->module . 'post' . $selname, $o);

include/acl_selectors.php call_hooks('acl_lookup_end', $results);

include/notifier.php: call_hooks('notifier_normal',$target_item);

include/notifier.php: call_hooks('notifier_end',$target_item);

include/items.php: call_hooks('atom_feed', $atom);

include/items.php: call_hooks('atom_feed_end', $atom);

include/items.php: call_hooks('atom_feed_end', $atom);

include/items.php: call_hooks('parse_atom', $arr);

include/items.php: call_hooks('post_remote',$arr);

include/items.php: call_hooks('atom_author', $o);

include/items.php: call_hooks('atom_entry', $o);

include/bb2diaspora.php: call_hooks('bb2diaspora',$Text);

include/cronhooks.php: call_hooks('cron', $d);

include/security.php: call_hooks('logged_in', $a->user);

include/html2bbcode.php: call_hooks('html2bbcode', $text);

include/Contact.php: call_hooks('remove_user',$r[0]);

include/Contact.php: call_hooks('contact_photo_menu', $args);

include/conversation.php: call_hooks('conversation_start',$cb);

include/conversation.php: call_hooks('render_location',$locate);

include/conversation.php: call_hooks('display_item', $arr);

include/conversation.php: call_hooks('render_location',$locate);

include/conversation.php: call_hooks('display_item', $arr);

include/conversation.php: call_hooks('item_photo_menu', $args);

include/conversation.php: call_hooks('jot_tool', $jotplugins);

include/conversation.php: call_hooks('jot_networks', $jotnets);

include/plugin.php:if(! function_exists('call_hooks')) {

include/plugin.php:function call_hooks($name, &$data = null) {

index.php: call_hooks('init_1');

index.php:call_hooks('app_menu', $arr);

index.php:call_hooks('page_end', $a->page['content']);

mod/photos.php: call_hooks('photo_post_init', $_POST);

mod/photos.php: call_hooks('photo_post_file',$ret);

mod/photos.php: call_hooks('photo_post_end',$foo);

mod/photos.php: call_hooks('photo_post_end',$foo);

mod/photos.php: call_hooks('photo_post_end',$foo);

mod/photos.php: call_hooks('photo_post_end',intval($item_id));

mod/photos.php: call_hooks('photo_upload_form',$ret);

mod/friendica.php: call_hooks('about_hook', $o);

mod/editpost.php: call_hooks('jot_tool', $jotplugins);

mod/editpost.php: call_hooks('jot_networks', $jotnets);

mod/parse_url.php: call_hooks('parse_link', $arr);

mod/home.php: call_hooks('home_init',$ret);

mod/home.php: call_hooks("home_content",$o);

mod/contacts.php: call_hooks('contact_edit_post', $_POST);

mod/contacts.php: call_hooks('contact_edit', $arr);

mod/settings.php: call_hooks('plugin_settings_post', $_POST);

mod/settings.php: call_hooks('connector_settings_post', $_POST);

mod/settings.php: call_hooks('settings_post', $_POST);

mod/settings.php: call_hooks('plugin_settings', $settings_addons);

mod/settings.php: call_hooks('connector_settings', $settings_connectors);

mod/settings.php: call_hooks('settings_form',$o);

mod/register.php: call_hooks('register_account', $newuid);

mod/like.php: call_hooks('post_local_end', $arr);

mod/xrd.php: call_hooks('personal_xrd', $arr);

mod/item.php: call_hooks('post_local_start', $_REQUEST);

mod/item.php: call_hooks('post_local',$datarray);

mod/item.php: call_hooks('post_local_end', $datarray);

mod/profile.php: call_hooks('profile_advanced',$o);

mod/profiles.php: call_hooks('profile_post', $_POST);

mod/profiles.php: call_hooks('profile_edit', $arr);

mod/tagger.php: call_hooks('post_local_end', $arr);

mod/cb.php: call_hooks('cb_init');

mod/cb.php: call_hooks('cb_post', $_POST);

mod/cb.php: call_hooks('cb_afterpost');

mod/cb.php: call_hooks('cb_content', $o);

mod/directory.php: call_hooks('directory_item', $arr);