# `UkCompanyNumber`

A UK company's number at Companies House, eight digits or two letters and six: `00445790`, `SC123456`.

[Tax and identity numbers](types.md#tax-and-identity-numbers); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its text, `UkCompanyNumber("00445790")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: UkCompanyNumber)` reads one from its text; text that isn't one at all fails `malformed`, such as `445790`, `sc123456` or `SC12345`.

## 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 |
|---|---|
| `00445790` | `"00445790"` |
| `SC123456` | `"SC123456"` |

It is stored in one column named for the field, of type `text`. `SC123456` is stored as `'SC123456'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `00445790` | `00445790` |
| `SC123456` | `SC123456` |

## 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.