---
title: "ViewHelpers"
manual: "Universal Messenger"
version: "main"
permalink: "https://docs.typo3.org/permalink/universal_messenger:usage-view-helpers@main"
source: "Usage/ViewHelpers.rst"
rendered: "2026-10-07T12:03:11+00:00"
---

# ViewHelpers {#usage-view-helpers}

## Initialization {#usage-view-helpers-initialization}

To use the extension's ViewHelpers in a Fluid template, declare their
namespace:

```html
xmlns:um="http://typo3.org/ns/Netresearch/UniversalMessenger/ViewHelpers"
```

## um:format.placeholder {#usage-view-helpers-format-placeholder}

Marks a value as a Universal Messenger placeholder using curly brackets,
so it can be passed as a literal placeholder inside a URL, for example the
unsubscribe link of a newsletter.

**Mark the "identifier" value as a Universal Messenger placeholder**

```html
<f:link.external uri="https://newsletter.example.org/unsubscribe?identifier={um:format.placeholder(value: 'identifier')}">
    Unsubscribe
</f:link.external>
```

This renders a URL of the form:

```text
https://newsletter.example.org/unsubscribe?identifier={identifier}
```

Universal Messenger replaces `{identifier}` with the actual value when
the newsletter is sent.