Linked Checkbox for TYPO3

form_element_linked_checkbox makes GDPR (UK: UK GDPR) consent genuinely clickable

The TYPO3 core form framework knows a checkbox but no checkbox with a linked label. Anyone working with the standard element cannot place a link to the privacy policy or to the terms and conditions inside the label, and that is exactly a requirement that comes up on every form in practice. The extension form_element_linked_checkbox closes this gap with a clean custom form element that combines text and link cleanly. For every TYPO3 installation that uses the native form framework, this extension is essentially mandatory. Without it, the only workaround is to extend the label text with a neighbouring text block, which does not only look untidy but is also problematic for screen readers and accessibility.

Typical use cases live in the compliance environment of every corporate site

The first and most common scenario are GDPR consent boxes below contact, newsletter and application forms. The text “I have read the privacy policy and consent to the processing of my data” has to contain a clickable link to /privacy, without the visitor having to tick the box in order to open it. form_element_linked_checkbox models exactly this case.

A second scenario is terms-and-conditions confirmations on registration and purchase forms. Universities use this for course bookings, associations for membership applications, e-commerce projects based on the TYPO3 form framework at checkout. Here, more than one link is often needed (terms, cancellation policy, privacy), all placed inside the same label.

The third scenario concerns double opt-in newsletters. Before signing up, the recipient has to explicitly confirm that they want to subscribe, with a link to newsletter-specific privacy information. form_element_linked_checkbox allows several checkboxes with their own link to be used in the same form, so that in addition to the privacy consent, the explicit newsletter consent can be asked for as a separate element. This matters, because GDPR requires separate consents and a blanket “I agree to everything” checkbox is not legally sufficient.

Technical architecture lives in the form framework plug-in system

The TYPO3 form framework is deliberately built to be extensible: every extension can register its own form elements, which show up in the YAML editor and are usable via drag and drop in the backend. form_element_linked_checkbox uses this mechanism and registers a new element “LinkedCheckbox” via the form setup YAML and the form element definitions area. Editors drag the element into their form just as they would drag a standard checkbox and configure label, link text and target in the detail panel.

Internally, the extension extends the checkbox class and adds properties for linkTarget, linkText and wrapLabel. Rendering runs through a dedicated Fluid partial that splits the label text into “before”, “linkText” and “after” and wraps the clickable area only around the link part. Clicking on the link opens the target page without toggling the checkbox. For accessibility this matters, because screen readers read the link as a separate element and the checkbox can be operated independently.

Configuration happens directly in the form framework YAML editor: after dragging the element into a form, the fields “Label before link”, “Link text”, “Label after link” and “Link target” appear in the right-hand detail column. The target can be an internal page, a file link or an external URL. Required field validation is set through the validators tab just like with the standard element.

Common problems involve multilingual content, styling and validator messages

The first support topic is translation. The label consists of three parts, and each part has to be maintained in every language separately. In practice that means: for a bilingual installation (DE/EN) the maintenance effort doubles. Anyone working with ext:l10nmgr should explicitly reference the LLL keys in the form definition, so that import/export works cleanly. A trick from larger projects: store the three label parts in a single LLL key with placeholders and assemble them server-side on output. That noticeably reduces the number of strings to be translated.

The second topic is styling. Many design systems work with custom checkboxes rebuilt in CSS from a span or label construct. The default template of the extension ships a simple wrapper that collides with some CSS frameworks. We recommend overriding the partial in the package overlay and aligning the structure with the rest of the form styling.

Thirdly, validator error messages are a common stumbling block. When the user does not click the checkbox, the message “Please agree to the privacy policy” should appear, not the default “Required field”. The extension supports custom error messages via formElementsDefinition in the form YAML; the message can be adjusted per element. For accessibility this matters, because screen readers read the error message aloud directly and unspecific messages give no help. We recommend phrasing every error message so that it is understandable independently of context.

TYPO3 v12 and v13 are fully supported, v10 migration needs a YAML adjustment

form_element_linked_checkbox is available for TYPO3 v11, v12 and v13. The YAML structure of the form framework has changed in details between v10 and v12, especially in the registration of custom elements. When upgrading a v10 installation, form definitions that use the element have to be moved to the new YAML syntax.

In Gosign projects we migrate the extension as part of the form framework refactoring, not individually. The effort is usually minimal because the element is referenced in every form only through its type identifier. During the migration we also check whether the GDPR consent texts are rendered correctly in every language after the TYPO3 upgrade and update the privacy links if they have changed in URL structure or text content.