# `PostalCode`

A postal code, `SW1A 1AA`, checked by its country's pattern where the country is known. Personal data.

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

## Make one

Build one from its text, `PostalCode("SW1A 1AA")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: PostalCode)` reads one from its text; text that isn't one at all fails `malformed`, such as `sw1a 1aa`, ` SW1A 1AA` or `SW1A 1AA `.

## 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 |
|---|---|
| `SW1A 1AA` | `"SW1A 1AA"` |
| `22162-1010` | `"22162-1010"` |
| `100-8994` | `"100-8994"` |

It is stored in one column named for the field, of type `text`. `22162-1010` is stored as `'22162-1010'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `SW1A 1AA` | `SW1A 1AA` |
| `22162-1010` | `22162-1010` |
| `100-8994` | `100-8994` |

## 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.