> For the complete documentation index, see [llms.txt](https://docs.pixiebrix.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pixiebrix.com/developing-mods/developer-concepts/text-template-guide/transforming-data-with-filters.md).

# Transforming Data with Filters

You can transform an expression by providing one or more filters in the template expression. Filters are provided using the `|` pipe operator.

For example, to upper case the pet’s name:

```
I have one {{ @pet.type }} named {{ @pet.name | upper }}
```

Will produce the following:

```html
I have one cat named TIGER
```

{% hint style="info" %}
A complete [list of supported filters is available here](https://mozilla.github.io/nunjucks/templating.html#builtin-filters). 
{% endhint %}

Some filters accept arguments. To pass arguments to a filter, include the arguments list in parentheses: `filter(arg1, arg2, ...)`

Popular transformation filters are:

* `title`: convert text to Title Case
* `truncate`: truncate the text with ellipses. For example: `@description | truncate(10)` to truncate text to 10 characters.
* `join`: concatenate values using a separator. For example: `@names | join(",")`

{% hint style="info" %}
Under the hood, PixieBrix uses the popular [Nunjucks templating language](https://mozilla.github.io/nunjucks/), developed by the non-profit that makes the Firefox web browser!
{% endhint %}


---

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