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: - :doc:`/admin/plugins` - :doc:`views` - :doc:`i18n` .. contents:: Contents :local: :depth: 2 Registering actions =================== Actions must be registered before use. There are two ways to register actions: Using ``elgg_register_action()`` .. code-block:: php 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`` .. code-block:: 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, ], ], ]; .. warning:: 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 :doc:`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``. .. code-block:: php [ 'blog/save' => [], // all defaults 'blog/delete' => [ // all custom 'access' => 'admin', 'filename' => __DIR__ . 'actions/blog/remove.php', ], ], ]; Permissions ----------- 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: .. code-block:: php elgg_register_action("example", $filepath, "public"); To restrict an action to only administrators, pass ``"admin"`` for the last parameter: .. code-block:: php elgg_register_action("example", $filepath, "admin"); To restrict an action to only logged out users, pass ``"logged_out"`` for the last parameter: .. code-block:: php elgg_register_action("example", $filepath, "logged_out"); Writing action files -------------------- Use the ``get_input()`` function to get access to request parameters: .. code-block:: php $field = get_input('input_field_name', 'default_value'); You can then use the :doc:`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) .. code-block:: php $user = get_entity($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()`` .. code-block:: php $user = elgg_get_logged_in_user_entity(); if (!$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: .. code-block:: php $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: .. code-block:: php 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; } elgg_register_error_message(elgg_echo('captcha:captchafail')); 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 ========================= ``entity/delete`` ----------------- If your plugin does not implement any custom logic when deleting an entity, you can use bundled delete action .. code-block:: php $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. .. code-block:: php // 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', ]; Forms ===== To output a form, use the elgg_view_form function like so: .. code-block:: php echo elgg_view_form('example'); Doing this generates something like the following markup: .. code-block:: html
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: .. code-block:: php // /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 elgg_set_form_footer(elgg_view('input/submit')); Now when you call ``elgg_view_form('example')``, Elgg will produce: .. code-block:: html
Inputs ------ 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. .. code-block:: php 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: .. code-block:: html 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). .. code-block:: php 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: .. code-block:: html
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/plaintext`` - renders a textarea ```` * ``input/longtext`` - renders a WYSIWYG text input * ``input/url`` - renders a url input ```` * ``input/email`` - renders an email input ```` * ``input/checkbox`` - renders a single checkbox ```` * ``input/checkboxes`` - renders a set of checkboxes with the same name * ``input/radio`` - renders one or more radio buttons ```` * ``input/submit`` - renders a submit button ```` * ``input/file`` - renders a file input ```` * ``input/select`` - renders a select input ```` * ``input/hidden`` - renders a hidden input ```` * ``input/password`` - renders a password input ```` * ``input/number`` - renders a number input ```` * ``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/grouppicker`` - renders an Elgg group autocomplete * ``input/objectpicker`` - renders an Elgg object autocomplete * ``input/location`` renders an Elgg location input Files and images ================ Use the ``input/file`` view in your form’s content view. .. code-block:: php // /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. .. code-block:: php if (get_input('icon_remove')) { $entity->deleteIcon(); } else { $entity->saveIconFromUploadedFile('icon'); } Set the enctype of the form to ``multipart/form-data``: .. code-block:: php echo elgg_view_form('example', array( 'enctype' => 'multipart/form-data' )); .. note:: 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: .. code-block:: php $icon = elgg_get_uploaded_file('icon'); Sticky forms ============ Sticky forms are forms that retain user input if saving fails. They are "sticky" because the user's data "sticks" in the form after submitting, though it was never saved to the database. This greatly improves the user experience by minimizing data loss. Elgg includes helper functions so you can make any form sticky. Helper functions ---------------- Sticky forms are implemented in Elgg by the following functions: - ``elgg_make_sticky_form($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)``. Overview -------- 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($name)``. .. note:: As of Elgg 5.0 forms rendered with ``elgg_view_form()`` can set the ``$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: .. code-block:: php // 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')) { extract(elgg_get_sticky_values('register')); elgg_clear_sticky_form('register'); } The registration action sets creates the sticky form and clears it once the action is completed: .. code-block:: php // actions/register.php elgg_make_sticky_form('register', ['password', 'password2']); elgg_register_user([ 'username' => $username, 'password' => $password, 'name' => $name, 'email' => $email, ]); elgg_clear_sticky_form('register'); .. tip:: The function ``elgg_make_sticky_form()`` supports an optional second argument ``$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: .. code-block:: php // 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()``: .. code-block:: php // 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: .. code-block:: php $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. .. code-block:: php // 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. Ajax ==== See the :doc:`Ajax guide` for instructions on calling actions from JavaScript. Security ======== 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: .. code-block:: php elgg_view('output/url', array('is_action' => true)); elgg_view('input/securitytoken'); $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: .. code-block:: php $__elgg_ts = elgg()->csrf->getCurrentTime()->getTimestamp(); $__elgg_token = elgg()->csrf->generateActionToken($__elgg_ts); You can also access the tokens from javascript: .. code-block:: js elgg.security.token.__elgg_ts; elgg.security.token.__elgg_token; 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. .. code-block:: php // 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: .. code-block:: php $mac = elgg_build_hmac([123, 456])->getToken(); // type of first array element differs elgg_build_hmac(["123", 456])->matchesToken($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. .. code-block:: php $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"); .. warning:: Signed URLs do not offer CSRF protection and should not be used instead of action tokens.