# `FamilyName`

A person's family name, one line as they write it.

Use it for a surname on its own, such as a list sorted by surname. When you hold a person's whole name, use [`PersonName`](/docs/types/type-person-name.md), which contains one.

## Shape

One value, held as text in one set form, with no parts: `山田`.

## Example

```jadpo
FamilyName("van der Berg")
```

`FamilyName(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: FamilyName)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as ` Somerville`.

## Good to know

- It takes any script and spaces inside, up to 200 characters. It refuses an empty name, spaces at either end and line breaks.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.
- A field that holds one counts as personal data (`identifying`), so you don't mark it yourself.

## In JSON

A string, in a request, a response or `json.write`:

```json
"Somerville"
"van der Berg"
"山田"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`FamilyName` is in the group People and contact, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `Somerville`, `van der Berg` and `山田`.

### How it is stored

It is stored in one column named for the field, of type `text`. `van der Berg` is stored as `'van der Berg'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `Somerville` | `Somerville` |
| `van der Berg` | `van der Berg` |
| `山田` | `山田` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>