# `InvoiceNumber`

An invoice's number (EN 16931): 1 to 200 characters, with no space at either end.

[Money and banking](types.md#money-and-banking); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its text, `InvoiceNumber("INV-2026-0042")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: InvoiceNumber)` reads one from its text; text that isn't one at all fails `malformed`, such as ` INV-1`, `INV-1 ` or `"INV\n1"`.

## 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 |
|---|---|
| `INV-2026-0042` | `"INV-2026-0042"` |
| `2026/17` | `"2026/17"` |

It is stored in one column named for the field, of type `text`. `2026/17` is stored as `'2026/17'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `INV-2026-0042` | `INV-2026-0042` |
| `2026/17` | `2026/17` |

## 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.