# Output and records

<PageBadges />

form0-core exposes two primary outputs:

- Engine state (`values`, `errors`, `visible`, `required`, `read_only`)
- Structured records for persistence (`createStructuredRecord`)

## Engine state

After `engine.eval()`, call `engine.getState()` to access the latest state.

## Structured record output

`createStructuredRecord` transforms engine state into a submission-friendly format:

- `form_values` uses field keys by default
- Repeatable sections become arrays of child records
- Sections are omitted (containers only)

### Field key mode

You can switch to `data_name` keys by using `fieldKeyMode`:

```js
const record = createStructuredRecord(state, fields, {
  fieldKeyMode: "data-name",
})
```

## Repeatable sections

Repeatable sections create nested records. Use `originalElements` to preserve the correct nesting
structure when building records.