Forms + Actions

Create, update, or delete content.

Elgg forms submit to actions. Actions define the behavior for form submission.

This guide assumes basic familiarity with:

Registering actions

Actions must be registered before use.

There are two ways to register actions:

Using elgg_register_action()

elgg_register_action("example", __DIR__ . "/actions/example.php");

The mod/example/actions/example.php script will now be run whenever a form is submitted to http://localhost/elgg/action/example.

Use elgg-plugin.php

return [
   'actions' => [
      // defaults to using an action file in /actions/myplugin/action_a.php
      'myplugin/action_a' => [
         'access' => 'public',

      // define custom action path
      'myplugin/action_b' => [
         'access' => 'admin',
         'filename' => __DIR__ . '/actions/action.php'

      // define a controller
      'myplugin/action_c' => [
         'controller' => \MyPlugin\Actions\ActionC::class,


A stumbling point for many new developers is the URL for actions. The URL always uses /action/ (singular) and never /actions/ (plural). However, action script files are usually saved under the directory /actions/ (plural) and always have an extension. Use elgg_generate_action_url() to avoid confusion.

Registering actions using plugin config file

You can also register actions via the elgg-plugin config file. To do this you need to provide an action section in the config file. The location of the action files are assumed to be in the plugin folder /actions.


return [
        'actions' => [
            'blog/save' => [], // all defaults
            'blog/delete' => [ // all custom
                  'access' => 'admin',
                  'filename' => __DIR__ . 'actions/blog/remove.php',


By default, actions are only available to logged in users.

To make an action available to logged out users, pass "public" as the third parameter:

elgg_register_action("example", $filepath, "public");

To restrict an action to only administrators, pass "admin" for the last parameter:

elgg_register_action("example", $filepath, "admin");

To restrict an action to only logged out users, pass "logged_out" for the last parameter:

elgg_register_action("example", $filepath, "logged_out");

Writing action files

Use the get_input() function to get access to request parameters:

$field = get_input('input_field_name', 'default_value');

You can then use the Database api to load entities and perform actions on them accordingly.

To indicate a successful action, use elgg_ok_response(). This function accepts data that you want to make available to the client for XHR calls (this data will be ignored for non-XHR calls)

$user = get_entity($guid);
// do something

$action_data = [
   'entity' => $user,
   'stats' => [
       'friends_count' => $user->getEntitiesFromRelationship([
           'type' => 'user',
           'relationship' => 'friend',
           'count' => true,

return elgg_ok_response($action_data, 'Action was successful', 'url/to/forward/to');

To indicate an error, use elgg_error_response()

$user = elgg_get_logged_in_user_entity();
if (!$user) {
   // show an error and forward the user to the referring page
   // send 404 error code on AJAX calls
   return elgg_error_response('User not found', REFERRER, ELGG_HTTP_NOT_FOUND);

if (!$user->canEdit()) {
   // show an error and forward to user's profile
   // send 403 error code on AJAX calls
   return elgg_error_response('You are not allowed to perform this action', $user->getURL(), ELGG_HTTP_FORBIDDEN);

Customizing actions

Before executing any action, Elgg triggers an event:

$result = elgg_trigger_event_results('action:validate', $action, [], true);

Where $action is the action being called. If the event returns false then the action will not be executed. Don’t return anything if your validation passes.

Example: Captcha

The captcha module uses this to intercept the register and user/requestnewpassword actions and redirect them to a function which checks the captcha code. This check returns false if the captcha validation fails (which prevents the associated action from executing).

This is done as follows:

elgg_register_event_handler("action:validate", "register", "captcha_verify_action_event");
elgg_register_event_handler("action:validate", "user/requestnewpassword", "captcha_verify_action_event");


function captcha_verify_action_event(\Elgg\Event $event) {
  $token = get_input('captcha_token');
  $input = get_input('captcha_input');

  if (($token) && (captcha_verify_captcha($input, $token))) {


  return false;

This lets a plugin extend an existing action without the need to replace the whole action. In the case of the captcha plugin it allows the plugin to provide captcha support in a very loosely coupled way.

Actions available in core


If your plugin does not implement any custom logic when deleting an entity, you can use bundled delete action

$guid = 123;
// You can provide optional forward path as a URL query parameter
$forward_url = 'path/to/forward/to';
echo elgg_view('output/url', array(
   'text' => elgg_echo('delete'),
   'href' => elgg_generate_action_url('entity/delete', [
     'guid' => $guid,
     'forward_url' => $forward_url,
   'confirm' => true,

You can customize the success message keys for your entity type and subtype, using "entity:delete:$type:$subtype:success" and "entity:delete:$type:success" keys.

// to add a custom message when a blog post or file is deleted
// add the translations keys in your language files
return [
   'entity:delete:object:blog:success' => 'Blog post has been deleted,
   'entity:delete:object:file:success' => 'File titled %s has been deleted',


To output a form, use the elgg_view_form function like so:

echo elgg_view_form('example');

Doing this generates something like the following markup:

<form action="http://localhost/elgg/action/example">
    <input type="hidden" name="__elgg_ts" value="1234567890" />
    <input type="hidden" name="__elgg_token" value="3874acfc283d90e34" />

Elgg does some things automatically for you when you generate forms this way:

  1. It sets the action to the appropriate URL based on the name of the action you pass to it

  2. It adds some anti-csrf tokens (__elgg_ts and __elgg_token) to help keep your actions secure

  3. It automatically looks for the body of the form in the forms/example view.

Put the content of your form in your plugin’s forms/example view:

// /mod/example/views/default/forms/example.php
echo elgg_view('input/text', array('name' => 'example'));

// defer form footer rendering
// this will allow other plugins to extend forms/example view

Now when you call elgg_view_form('example'), Elgg will produce:

<form action="http://localhost/elgg/action/example">
    <input type="hidden" name="__elgg_ts" value="...">
    <input type="hidden" name="__elgg_token" value="...">

    <input type="text" class="elgg-input-text" name="example">
    <div class="elgg-foot elgg-form-footer">
        <input type="submit" class="elgg-button elgg-button-submit" value="Submit">


To render a form input, use one of the bundled input views, which cover all standard HTML input elements. See individual view files for a list of accepted parameters.

echo elgg_view('input/select', array(
   'required' => true,
   'name' => 'status',
   'options_values' => [
      'draft' => elgg_echo('status:draft'),
      'published' => elgg_echo('status:published'),
   // most input views will render additional parameters passed to the view
   // as tag attributes
   'data-rel' => 'blog',

The above example will render a dropdown select input:

<select required="required" name="status" data-rel="blog" class="elgg-input-select">
   <option value="draft">Draft</option>
   <option value="published">Published</option>

To ensure consistency in field markup, use elgg_view_field(), which accepts all the parameters of the input being rendered, as well as #label and #help parameters (both of which are optional and accept HTML or text).

echo elgg_view_field([
   '#type' => 'select',
   '#label' => elgg_echo('blog:status:label'),
   '#help' => elgg_view_icon('help') . elgg_echo('blog:status:help'),
   'required' => true,
   'name' => 'status',
   'options_values' => [
      'draft' => elgg_echo('status:draft'),
      'published' => elgg_echo('status:published'),
   'data-rel' => 'blog',

The above will generate the following markup:

<div class="elgg-field elgg-field-required">
   <label for="elgg-field-1" class="elgg-field-label">Blog status<span title="Required" class="elgg-required-indicator">*</span></label>
   <div class="elgg-field-input">
      <select required="required" name="status" data-rel="blog" id="elgg-field-1" class="elgg-input-select">
         <option value="draft">Draft</option>
         <option value="published">Published</option>
   <div class="elgg-field-help elgg-text-help">
      <span class="elgg-icon-help elgg-icon"></span>This indicates whether or not the blog is visible in the feed

Input types

A list of bundled input types/views:

  • input/text - renders a text input <input type="text">

  • input/plaintext - renders a textarea <textarea></textarea>

  • input/longtext - renders a WYSIWYG text input

  • input/url - renders a url input <input type="url">

  • input/email - renders an email input <input type="email">

  • input/checkbox - renders a single checkbox <input type="checkbox">

  • input/checkboxes - renders a set of checkboxes with the same name

  • input/radio - renders one or more radio buttons <input type="radio">

  • input/submit - renders a submit button <button type="submit">

  • input/button - renders a button <button></button>

  • input/file - renders a file input <input type="file">

  • input/select - renders a select input <select></select>

  • input/hidden - renders a hidden input <input type="hidden">

  • input/password - renders a password input <input type="password">

  • input/number - renders a number input <input type="number">

  • input/date - renders a jQuery datepicker

Elgg offers some helper input types

  • input/access - renders an Elgg access level select

  • input/tags - renders an Elgg tags input

  • input/autocomplete - renders an Elgg entity autocomplete

  • input/captcha - placeholder view for plugins to extend

  • input/friendspicker - renders an Elgg friend autocomplete

  • input/userpicker - renders an Elgg user autocomplete

  • input/location renders an Elgg location input

Files and images

Use the input/file view in your form’s content view.

// /mod/example/views/default/forms/example.php
echo elgg_view('input/file', ['name' => 'icon']);

If you wish to upload an icon for entity you can use the helper view entity/edit/icon. This view shows a file input for uploading a new icon for the entity, an thumbnail of the current icon and the option to remove the current icon.

The view supports some variables to control the output

  • entity - the entity to add/remove the icon for. If provided based on this entity the thumbnail and remove option wil be shown

  • entity_type - the entity type for which the icon will be uploaded. Plugins could find this useful, maybe to validate icon sizes

  • entity_subtype - the entity subtype for which the icon will be uploaded. Plugins could find this useful, maybe to validate icon sizes

  • icon_type - the type of the icon (default: icon)

  • name - name of the input/file (default: icon)

  • remove_name - name of the remove icon toggle (default: $vars[‘name’] . ‘_remove’)

  • required - is icon upload required (default: false)

  • cropper_enabled - is icon cropping allowed (default: true)

  • show_remove - show the remove icon option (default: true)

  • show_thumb - show the thumb of the entity if available (default: true)

  • thumb_size - the icon size to use as the thumb (default: medium)

If using the helper view you can use the following code in you action to save the icon to the entity or remove the current icon.

if (get_input('icon_remove')) {
} else {

Set the enctype of the form to multipart/form-data:

echo elgg_view_form('example', array(
  'enctype' => 'multipart/form-data'


The enctype of all forms that use the method POST defaults to multipart/form-data.

In your action file, use elgg_get_uploaded_file('your-input-name') to access the uploaded file:

$icon = elgg_get_uploaded_file('icon');

Sticky forms

Sticky forms are forms that retain user input if saving fails. They are “sticky” because the user’s data “sticks” in the form after submitting, though it was never saved to the database. This greatly improves the user experience by minimizing data loss. Elgg includes helper functions so you can make any form sticky.

Helper functions

Sticky forms are implemented in Elgg by the following functions:

  • elgg_make_sticky_form($name) - Tells the engine to make all input on a form sticky.

  • elgg_clear_sticky_form($name) - Tells the engine to discard all sticky input on a form.

  • elgg_is_sticky_form($name) - Checks if $name is a valid sticky form.

  • elgg_get_sticky_values($name) - Returns all sticky values saved for $name by elgg_make_sticky_form($name).


The basic flow of using sticky forms is:

  1. Call elgg_make_sticky_form($name) at the top of actions for forms you want to be sticky.

  2. Use elgg_is_sticky_form($name) and elgg_get_sticky_values($name) to get sticky values when rendering a form view.

  3. Call elgg_clear_sticky_form($name) after the action has completed successfully or after data has been loaded by elgg_get_sticky_values($name).


As of Elgg 5.0 forms rendered with elgg_view_form() can set the $form_vars['sticky_enabled'] = true flag to automatically get sticky form support. The submitted values to the action will automatically be filled in the $body_vars when an error occured in the action.

elgg_view_form() supports the following $form_vars to help with sticky form support:

  • sticky_enabled: a bool to enable automatic sticky form support

  • sticky_form_name: an optional string to set where the sticky form values are saved. This defaults to the $action_name and should only be changed if the $action_name is different from the actual action

  • sticky_ignored_fields: an ``array with the names fo the form fields that should be saved. For example password fields

Example: User registration

Simple sticky forms require little logic to determine the input values for the form. This logic is placed at the top of the form body view itself.

The registration form view first sets default values for inputs, then checks if there are sticky values. If so, it loads the sticky values before clearing the sticky form:

// views/default/forms/register.php
$password = $password2 = '';
$username = get_input('u');
$email = get_input('e');
$name = get_input('n');

if (elgg_is_sticky_form('register')) {

The registration action sets creates the sticky form and clears it once the action is completed:

// actions/register.php
elgg_make_sticky_form('register', ['password', 'password2']);

   'username' => $username,
   'password' => $password,
   'name' => $name,
   'email' => $email,



The function elgg_make_sticky_form() supports an optional second argument $ignored_field_names. This needs to be an array of the field names you don’t wish to be made sticky. This is usefull for fields which contain sensitive data, like passwords.

Example: Bookmarks

The bundled plugin Bookmarks’ save form and action is an example of a complex sticky form.

The form view for the save bookmark action uses elgg_extract() to pull values from the $vars array:

// mod/bookmarks/views/default/forms/bookmarks/save.php
$title = elgg_extract('title', $vars, '');
$desc = elgg_extract('description', $vars, '');
$address = elgg_extract('address', $vars, '');
$tags = elgg_extract('tags', $vars, '');
$access_id = elgg_extract('access_id', $vars, ACCESS_DEFAULT);
$container_guid = elgg_extract('container_guid', $vars);
$guid = elgg_extract('guid', $vars, null);
$shares = elgg_extract('shares', $vars, array());

The page handler scripts enables sticky form support by passing the correct values to elgg_view_form():

// mod/bookmarks/pages/add.php
$content = elgg_view_form('bookmarks/save', ['sticky_enabled' => true]);

Similarly, mod/bookmarks/pages/edit.php uses the same sticky support, but passes the entity that is being edited:

$bookmark_guid = get_input('guid');
$bookmark = get_entity($bookmark_guid);


$content = elgg_view_form('bookmarks/save', ['sticky_enabled' => true], ['entity' => $bookmark]);

The plugin has an event listener on the 'form:prepare:fields', 'bookmarks/save' event and the handler does 2 things:

  1. Defines the input names and default values for form inputs.

  2. Extracts the values from a bookmark object if it’s passed.

// mod/bookmarks/classes/Elgg/Bookmarks/Forms/PrepareFields.php
      * Prepare the fields for the bookmarks/save form
      * @since 5.0
     class PrepareFields {

              * Prepare fields
              * @param \Elgg\Event $event 'form:prepare:fields', 'bookmarks/save'
              * @return array|null
             public function __invoke(\Elgg\Event $event): ?array {
                     $vars = $event->getValue();

                     // input names => defaults
                     $values = [
                             'title' => get_input('title', ''), // bookmarklet support
                             'address' => get_input('address', ''),
                             'description' => '',
                             'access_id' => ACCESS_DEFAULT,
                             'tags' => '',
                             'container_guid' => elgg_get_page_owner_guid(),
                             'guid' => null,

                     $bookmark = elgg_extract('entity', $vars);
                     if ($bookmark instanceof \ElggBookmark) {
                             // load current bookmark values
                             foreach (array_keys($values) as $field) {
                                     if (isset($bookmark->$field)) {
                                             $values[$field] = $bookmark->$field;

                     return array_merge($vars, $values);

The save action doesn’t need to do anything with sticky form support as this is all handled by the system.


See the Ajax guide for instructions on calling actions from JavaScript.


For enhanced security, all actions require an CSRF token. Calls to action URLs that do not include security tokens will be ignored and a warning will be generated.

A few views and functions automatically generate security tokens:

elgg_view('output/url', array('is_action' => true));
$url = elgg_add_action_tokens_to_url("http://localhost/elgg/action/example");
$url = elgg_generate_action_url('myplugin/myaction');

In rare cases, you may need to generate tokens manually:

$__elgg_ts = elgg()->csrf->getCurrentTime()->getTimestamp();
$__elgg_token = elgg()->csrf->generateActionToken($__elgg_ts);

You can also access the tokens from javascript:;;

These are refreshed periodically so should always be up-to-date.

Security Tokens

On occasion we need to pass data through an untrusted party or generate an “unguessable token” based on some data. The industry-standard HMAC algorithm is the right tool for this. It allows us to verify that received data were generated by our site, and were not tampered with. Note that even strong hash functions like SHA-2 should not be used without HMAC for these tasks.

Elgg provides elgg_build_hmac() to generate and validate HMAC message authentication codes that are unguessable without the site’s private key.

// generate a querystring such that $a and $b can't be altered
$a = 1234;
$b = "hello";
$query = http_build_query([
    'a' => $a,
    'b' => $b,
    'mac' => elgg_build_hmac([$a, $b])->getToken(),
$url = "action/foo?$query";

// validate the querystring
$a = (int) get_input('a', '', false);
$b = (string) get_input('b', '', false);
$mac = get_input('mac', '', false);

if (elgg_build_hmac([$a, $b])->matchesToken($mac)) {
    // $a and $b have not been altered

Note: If you use a non-string as HMAC data, you must use types consistently. Consider the following:

$mac = elgg_build_hmac([123, 456])->getToken();

// type of first array element differs
elgg_build_hmac(["123", 456])->matchesToken($mac); // false

// types identical to original
elgg_build_hmac([123, 456])->matchesToken($mac); // true

Signed URLs

Signed URLs offer a limited level of security for situations where action tokens are not suitable, for example when sending a confirmation link via email. URL signatures verify that the URL has been generated by your Elgg installation (using site secret) and that the URL query elements were not tampered with.

URLs a signed with an unguessable SHA-256 HMAC key. See Security Tokens for more details.

$url = elgg_http_add_url_query_element(elgg_normalize_url('confirm'), [
   'user_guid' => $user_guid,

$url = elgg_http_get_signed_url($url);

notify_user($user_guid, $site->guid, 'Confirm', "Please confirm by clicking this link: $url");


Signed URLs do not offer CSRF protection and should not be used instead of action tokens.