> ## Documentation Index
> Fetch the complete documentation index at: https://docs.alumio.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Render a Template

> Practical examples for rendering output with the Render a Template Transformer, using variable interpolation, loops, conditionals, and built-in filters.

### Overview

The Render a Template Transformer renders Twig templates using supplied data to produce formatted output strings, such as order confirmations, emails, CSV rows, or HTML/XML blocks. For safety, only the `if` and `for` tags are supported, along with a fixed set of filters: `abs`, `batch`, `capitalize`, `default`, `escape` (`e`), `first`, `format`, `join`, `keys`, `last`, `length`, `lower`, `nl2br`, `number_format`, `replace`, `reverse`, `round`, `striptags`, `title`, `trim`, `upper`, and `url_encode`.

### Render a confirmation message

```twig theme={null}
Dear {{ customer.firstName }} {{ customer.lastName }}, your order #{{ order.id }} totaling {{ order.total|number_format(2) }} {{ order.currency }} has been received and is being processed.
```

Sample data:

```json theme={null}
{
  "customer": { "firstName": "Maria", "lastName": "Janssen" },
  "order": { "id": "ORD-10293", "total": 149.5, "currency": "EUR" }
}
```

Output:

```text theme={null}
Dear Maria Janssen, your order #ORD-10293 totaling 149.50 EUR has been received and is being processed.
```

### Loop over items to build a CSV block

```twig theme={null}
{% for item in order.items %}{{ item.sku }},{{ item.name }},{{ item.quantity }},{{ item.price|number_format(2) }}
{% endfor %}
```

Sample data:

```json theme={null}
{
  "order": {
    "items": [
      { "sku": "SKU-001", "name": "Wireless Mouse", "quantity": 2, "price": 19.99 },
      { "sku": "SKU-002", "name": "USB-C Cable", "quantity": 5, "price": 8.5 }
    ]
  }
}
```

Output:

```text theme={null}
SKU-001,Wireless Mouse,2,19.99
SKU-002,USB-C Cable,5,8.50
```

### Use a conditional fallback

```twig theme={null}
{% if customer.address.street is defined %}
{{ customer.address.street }} {{ customer.address.houseNumber }}, {{ customer.address.postalCode }} {{ customer.address.city }}
{% else %}
No address on file
{% endif %}
```

<Note>
  Only the `if` and `for` tags are available in the Render a Template Transformer. Constructs like `{% set %}` are not supported.
</Note>

### Text formatting filters

| Filter                 | Example                                                      | Result              |
| ---------------------- | ------------------------------------------------------------ | ------------------- |
| `trim` + `title`       | `{{ product.name\|trim\|title }}`                            | `Wireless Keyboard` |
| `default` + `upper`    | `{{ product.brand\|default('Unknown Brand', true)\|upper }}` | `UNKNOWN BRAND`     |
| `lower` + `capitalize` | `{{ product.category\|lower\|capitalize }}`                  | `Electronics`       |

### List filters

| Filter    | Example                                                   | Result                     |
| --------- | --------------------------------------------------------- | -------------------------- |
| `join`    | `{{ order.items\|join(', ') }}`                           | `Mouse, Keyboard, Monitor` |
| `first`   | `{{ order.items\|first }}`                                | `Mouse`                    |
| `last`    | `{{ order.items\|last }}`                                 | `Monitor`                  |
| `length`  | `{{ order.items\|length }}`                               | `3`                        |
| `reverse` | `{{ order.items\|reverse\|join(', ') }}`                  | `Monitor, Keyboard, Mouse` |
| `batch`   | `{% for group in order.items\|batch(2) %}...{% endfor %}` | groups of 2                |
| `keys`    | `{{ product.attributes\|keys\|join(', ') }}`              | `color, size, material`    |

### Numeric filters

| Filter          | Example                                                                | Result                               |
| --------------- | ---------------------------------------------------------------------- | ------------------------------------ |
| `abs`           | `{{ invoice.amount\|abs }}`                                            | `149.5678`                           |
| `round`         | `{{ invoice.amount\|abs\|round(2) }}`                                  | `149.57`                             |
| `number_format` | `{{ invoice.amount\|abs\|number_format(2) }}`                          | `149.57`                             |
| `format`        | `{{ '%s costs %.2f EUR'\|format(product.name, invoice.amount\|abs) }}` | `Wireless Keyboard costs 149.57 EUR` |

### Safety and escaping filters

| Filter                | Example                                                 | Result                              |
| --------------------- | ------------------------------------------------------- | ----------------------------------- |
| `striptags` + `nl2br` | `{{ review.comment\|striptags\|nl2br }}`                | HTML tags removed, line breaks kept |
| `escape` (`e`)        | `{{ review.comment\|escape }}`                          | HTML entities escaped               |
| `replace`             | `{{ review.comment\|replace({'great': 'excellent'}) }}` | word replaced                       |
| `url_encode`          | `{{ review.authorEmail\|url_encode }}`                  | URL-safe string                     |

<Tip>
  Use the **Run Test** option in Alumio after each change to validate the rendered output against a representative entity before enabling the configuration.
</Tip>