# `Username`

A login handle: lower-case letters, digits, `_`, `.` and `-`, 1 to 64 of them. Personal data.

[People and contact](types.md#people-and-contact); not ordered; personal data (identifying); since Jadpo 0.1.0.

## Make one

Build one from its text, `Username("mary")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: Username)` reads one from its text; text that isn't one at all fails `malformed`, such as `Mary`, `mary somerville` or `mary@example.com`.

## Text, JSON and storage

`text.from` writes its canonical text, the one form `text.parse` reads back. JSON sends its canonical text as a string.

| Text | JSON |
|---|---|
| `mary` | `"mary"` |
| `mary.somerville_1780` | `"mary.somerville_1780"` |

It is stored in one column named for the field, of type `text`. `mary.somerville_1780` is stored as `'mary.somerville_1780'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `mary` | `mary` |
| `mary.somerville_1780` | `mary.somerville_1780` |

## Operations

It has the contract's own operations: `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. It isn't ordered, so `<` and sorting don't take it. [Every standard type meets one contract](../topics/every-standard-type-meets-one-contract.md) says how they work.