# `UkNationalInsuranceNumber`

A UK National Insurance number, its prefix one HMRC allocates: `AB123456C`, shown to people as `AB 12 34 56 C`. Personal data.

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

## Make one

Build one from its text, `UkNationalInsuranceNumber("AB123456C")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: UkNationalInsuranceNumber)` reads one from its text; text that isn't one at all fails `malformed`, such as `QQ123456C`, `GB123456A` or `AO123456A`.

## 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 |
|---|---|
| `AB123456C` | `"AB123456C"` |
| `CE987654A` | `"CE987654A"` |

It is stored in one column named for the field, of type `text`. `CE987654A` is stored as `'CE987654A'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `AB123456C` | `AB 12 34 56 C` |
| `CE987654A` | `CE 98 76 54 A` |

## 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.