Version 5 supported

Rich-text editing (WYSIWYG)

Editing and formatting content is the bread and butter of every content management system, which is why Silverstripe CMS has a tight integration with our preferred editor library, TinyMCE.

On top of the base functionality, we use our own insertion dialogs to ensure you can effectively select and upload files. We also use shortcodes to store information about inserted images or media elements.

The framework comes with a HTMLEditorField form field class which encapsulates most of the required functionality. It is usually added through the DataObject::getCMSFields() method:

// app/src/Model/MyObject.php
namespace App\Model;

use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\HTMLEditor\HTMLEditorField;
use SilverStripe\ORM\DataObject;

class MyObject extends DataObject
    private static $db = [
        'Content' => 'HTMLText',

    public function getCMSFields()
        return FieldList::create(

Specify which configuration to use

By default, a config named 'CMS' is used in any new HTMLEditorField.

If you have created your own HTMLEditorConfig and would like to use it, you can call HTMLEditorConfig::set_active('myConfig') and all subsequently created HTMLEditorField instances will use the configuration with the name 'myConfig'.

You can also specify which HTMLEditorConfig to use on a per field basis via the construct argument. This is particularly useful if you need different configurations for multiple HTMLEditorField on the same page or form.

namespace App\Model;

use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\HTMLEditor\HTMLEditorField;
use SilverStripe\ORM\DataObject;

class MyObject extends DataObject
    private static $db = [
        'Content' => 'HTMLText',
        'OtherContent' => 'HTMLText',

    public function getCMSFields()
        return FieldList::create([
            HTMLEditorField::create('OtherContent', 'Other content', $this->OtherContent, 'myConfig'),

In the above example, the 'Content' field will use the default 'CMS' config while 'OtherContent' will be using 'myConfig'.


To keep the JavaScript editor configuration manageable and extensible, we've wrapped it in a PHP class called HTMLEditorConfig. The class comes with its own defaults, which are extended through the Configuration API in the framework (and the cms module in case you've got that installed).

There can be multiple configs, which should always be created / accessed using HTMLEditorConfig::get(). You can then set the currently active config using HTMLEditorConfig::set_active().

The order in which the _config.php files are executed depends on the module names. Execution order is alphabetical, so if you set a TinyMCE option in the aardvark/_config.php (i.e. the module name is simply aardvark), this will be overridden in vendor/silverstripe/admin/_config.php (because the module name is silverstripe/admin) and your modification will disappear.

Adding and removing capabilities

In its simplest form, the configuration of the editor includes adding and removing buttons and plugins.

You can add plugins to the editor using the Framework's TinyMCEConfig::enablePlugins() method. This will transparently generate the relevant underlying TinyMCE code.

The enablePlugins() method is implemented on TinyCMEConfig, which is a subclass of HTMLEditorConfig. This is true of most of the configuration methods used in this documentation. We've done an explicit instanceof check here for correctness, but in reality unless your project introduces an alternative WYSIWYG editor, you can safely omit that check. The remaining examples in this documentation will omit the check.

// app/_config.php
use SilverStripe\Forms\HTMLEditor\HTMLEditorConfig;
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;

$editorConfig = HTMLEditorConfig::get('cms');
if ($editorConfig instanceof TinyMCEConfig) {

This utilities the TinyMCE's external_plugins option under the hood.

Plugins and advanced themes can provide additional buttons that can be added (or removed) through the configuration. Here is an example of adding a ssmacron button after the charmap button:

// app/_config.php
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;
TinyMCEConfig::get('cms')->insertButtonsAfter('charmap', 'ssmacron');

Buttons can also be removed:

// app/_config.php
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;
TinyMCEConfig::get('cms')->removeButtons('tablecontrols', 'blockquote', 'hr');

Internally HTMLEditorConfig uses the TinyMCE's toolbar option to configure these. See the TinyMCE documentation of this option for more details.

Setting options

TinyMCE behaviour can be affected through its configuration options. These options will be passed straight to the editor.

One example of the usage of this capability is to redefine the TinyMCE's whitelist of HTML tags - the tags that will not be stripped from the HTML source by the editor.

// app/_config.php
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;

// Add start and type attributes for <ol>, add <embed> with all attributes.
    'img[class|src|alt|title|hspace|vspace|width|height|align|name|usemap|data*],' .
    'iframe[src|name|width|height|align|frameborder|marginwidth|marginheight|scrolling],' .
    'object[width|height|data|type],' .
    'embed[src|type|pluginspage|width|height|autoplay],' .
    'param[name|value],' .
    'map[class|name|id],' .
    'area[shape|coords|href|target|alt],' .

Note that the setOption() overrides any existing value for that option. If you only want to change some small part of the existing option value, you can call getOption(), modify the returned value, and then pass the result to setOption().

// app/_config.php
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;

// Add start and type attributes for <ol>, add <embed> with all attributes - without redeclaring everything else
$editor = TinyMCEConfig::get('cms');
$validElements = $editor->getOption('extended_valid_elements') . ',' .
    'embed[src|type|pluginspage|width|height|autoplay],' .
$validElements = str_replace('iframe[', 'iframe[data-*|');
$editor->setOption('extended_valid_elements', $validElements);

The default setting for the CMS's extended_valid_elements we are overriding here can be found in vendor/silverstripe/admin/_config.php.

Enabling custom plugins

It is also possible to add custom plugins to TinyMCE, for example toolbar buttons. You can enable them through TinyMCEConfig::enablePlugins():

// app/_config.php
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;
TinyMCEConfig::get('cms')->enablePlugins(['myplugin' => 'app/javascript/myplugin/editor_plugin.js']);

The path for the plugin file must be one of the following:

  • null (if the plugin being enabled is a built-in plugin)
  • a path, relative to your _resources/ directory, to the plugin file
  • a ModuleResource instance representing the plugin JavaScript file (see silverstripe/admin's _config.php file for examples)
  • an absolute URL (e.g. for a third-party plugin to be fetched from a CDN).

You can learn how to create a plugin from the TinyMCE documentation.

Image and media insertion

The HTMLEditorField API also handles inserting images and media files into the managed HTML content. It can be used both for referencing files on the webserver filesystem (through the File and Image APIs), as well as hotlinking files from the web.

We use shortcodes to store information about inserted images or media elements. The ShortcodeParser API post-processes the HTML content on rendering, and replaces the shortcodes accordingly. It also takes care of care of placing the shortcode replacements relative to its surrounding markup (e.g. left/right alignment).

Image size pre-sets

Silverstripe CMS will suggest pre-set image size in the HTMLEditor. Editors can quickly switch between the pre-set size when interacting with images in the HTMLEditorField.

The default values are "Best fit" (600 pixels width) and original size. Developers can customise the pre-set sizes by altering their TinyMCEConfig.

You can alter the defaults for all HTMLEditor in your YAML configuration.

    - name: widesize
      i18n: SilverStripe\Forms\HTMLEditor\TinyMCEConfig.WIDE_SIZE
      text: Wide size
      width: 900

You can edit the image size pre-sets for an individual configuration with this code snippet.

use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;

TinyMCEConfig::get('cms')->setOption('image_size_presets', [
        'width' => 300,
        'text' => 'Small fit',
        'name' => 'smallfit',
        'default' => true,
        'width' => 600,
        'i18n' => TinyMCEConfig::class . '.BEST_FIT',
        'text' => 'Best fit',
        'name' => 'bestfit',
        'i18n' => TinyMCEConfig::class . '.ORIGINAL_SIZE',
        'text' => 'Original size',
        'name' => 'originalsize',

OEmbed: embedding media through external services

The "oEmbed" standard is implemented by many media services around the web, allowing easy representation of files just by referencing a website URL. For example, a content author can insert a playable youtube video just by knowing its URL, as opposed to dealing with manual HTML code.

oEmbed powers the "Insert from web" feature available through HTMLEditorField. Internally this service is provided by the embed library.

To disable oembed you will need to follow the below to remove the plugin from TinyMCE, as well as disabling the internal service via YAML:

Name: oembed-disable
  enabled: false
use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;

Use the following config if you need to send outbound requests through a proxy:

Name: myembed
After: coreoembed
      - proxy: '111.222.333.444:55'

Limiting oembed URLs

HTMLEditorField can have whitelists set on both the scheme (default HTTP & HTTPS) and domains allowed when inserting files for use with oembed.

This is performed through the config variables on the RemoteFileFormFactory class:

Name: oembed-restrictions
    - https
    - http
    - ftp
    - localhost
    - 80
    - 443
    - 23

This allows a white or blacklist to be applied to schema, domain, or port (if provided). Note that both blacklist and whitelist need to match, and are only ignored if the rules are empty for any of the above values.

By default live sites (see environment types) will not attempt to resolve oembed urls that point to localhost to protect your site from cross site request forgery.


Since TinyMCE generates markup, it needs to know which doctype your documents will be rendered in. You can set this through the element_format configuration variable.

In case you want to adhere to the stricter xhtml format (for example rendering self closing tags like <br/> instead of <br>), use the following configuration:

use SilverStripe\Forms\HTMLEditor\TinyMCEConfig;
TinyMCEConfig::get('cms')->setOption('element_format', 'xhtml');

By default, TinyMCE and Silverstripe CMS will generate valid HTML5 markup, but it will strip out many HTML5 tags like <article> or <figure>. If you plan to use those, add them to the valid_elements configuration setting.

Also, the HTMLValue API underpinning the HTML processing parses the markup into a temporary object tree which can be traversed and modified before saving. The built-in parser supports HTML5 syntax.

Security groups with their own editor configuration

Different groups of authors can be assigned their own config, e.g. a more restricted rule set for content reviewers (see access control). The config is available on each user record through Member::getHTMLEditorConfigForCMS(). The group assignment is done through the "Security" interface for each Group record. Note: The dropdown is only available if more than one config exists.

Customising modal forms

In the standard installation, you can insert links (internal/external/anchor/email), images as well as flash media files. The forms used for preparing the new content element are rendered by Silverstripe CMS, but there's some JavaScript involved to transfer back and forth between a content representation the editor can understand, present and save.

The forms for these actions are created using implementations of the FormFactory interface. For example, the module for embedding remote files gets its form from the RemoteFileFormFactory class.

All of these forms can be customised by implementing an extension with the appropriate extension hook method.

Example: Remove field for "Caption" in the embedded image form:

// app/src/Extension/MyToolbarExtension.php
namespace App\Extension;

use SilverStripe\Core\Extension;
use SilverStripe\Forms\Form;

class RemoteFileFormFactoryExtension extends Extension
    public function updateForm(Form $form)
# app/_config/extensions.yml
    - App\Extension\RemoteFileFormFactoryExtension

Adding functionality is a bit more advanced, you'll most likely need to add some fields to the PHP forms, as well as write some JavaScript to ensure the values from those fields make it into the content elements (and back out in case an existing element gets edited).

Using the HTMLEditorField outside of the CMS

The HTMLEditorField is configured for use in the CMS interface - but it can be used in other contexts as well, with some additional configuration. Note however that use of the ssmedia and sslink and related plugins is not directly supported outside of the CMS. Your best bet is to configure a custom HTMLEditorConfig for this purpose which doesn't include those plugins.

You will also need to provide some basic JavaScript to initialise the TinyMCE field. The below JavaScript will initialise TinyMCE configuration for every HTMLEditorField on the page:

// eslint-disable-next-line no-restricted-syntax
for (const field of document.querySelectorAll('textarea[data-editor="tinyMCE"]')) {
  const id = field.getAttribute('id');
  const config = JSON.parse(field.dataset.config);
  config.selector = `#${id}`;
  if (typeof config.baseURL !== 'undefined') {
    tinymce.EditorManager.baseURL = config.baseURL;

Developing a wrapper to use a different WYSIWYG editors with HTMLEditorField

WYSIWYG editors are complex beasts, so replacing it completely is a difficult task. The framework provides a wrapper implementation for the basic required functionality, mainly around selecting and inserting content into the editor view. Have a look in HTMLEditorField.js and the ss.editorWrapper object to get you started on your own editor wrapper. Note that the JavaScript for the HTMLEditorField is currently hardwired to support TinyMCE, and it is likely that a lot of projects and modules will be expecting all HTMLEditorConfig instances to be TinyMCEConfig instances.