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

# Transform Expressions

> Modify form data before saving to the account

## Enable Transforms

<Steps>
  <Step title="Add Fields">
    Add your form fields
  </Step>

  <Step title="Enable">
    Toggle **Transform data before saving**
  </Step>
</Steps>

## Write Transform Expression

Use JSONata to modify the form data. The expression should return the transformed object.

### Example: Add Computed Field

Count selected projects and add timestamp:

```jsonata theme={null}
$merge([
  $,
  {
    "total_projects": $count(projects),
    "configured_at": $now()
  }
])
```

**Input:**

```json theme={null}
{
  "warehouse_id": "wh-123",
  "projects": [{"value": "1"}, {"value": "2"}]
}
```

**Output:**

```json theme={null}
{
  "warehouse_id": "wh-123",
  "projects": [{"value": "1"}, {"value": "2"}],
  "total_projects": 2,
  "configured_at": "2024-01-15T10:30:00Z"
}
```

### Example: Flatten Values

Extract just the IDs from selections:

```jsonata theme={null}
{
  "warehouse_id": warehouse_id,
  "project_ids": projects.value
}
```

**Output:**

```json theme={null}
{
  "warehouse_id": "wh-123",
  "project_ids": ["1", "2"]
}
```

## Common Functions

| Function            | Description       |
| ------------------- | ----------------- |
| `$merge([a, b])`    | Combine objects   |
| `$count(array)`     | Count items       |
| `$now()`            | Current timestamp |
| `$sum(array)`       | Sum numbers       |
| `$join(array, sep)` | Join strings      |