# `FlightNumber`

A flight's designator (IATA's SSIM), written `BA123`: its airline, its number from 1 to 9999 and any suffix.

[Travel](types.md#travel); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its fields, `FlightNumber { airline: ...  number: ... }`.

`text.parse(raw, as: FlightNumber)` reads one from its text; text that isn't one at all fails `malformed`, such as `BA0123`, `BA 123` or `ba123`.

## Fields

| Field | Type |
|---|---|
| `airline` | [`IataAirline`](type-iata-airline.md) |
| `number` | `Int` |
| `suffix` | `Text?` |

## 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 |
|---|---|
| `BA123` | `"BA123"` |
| `U21234` | `"U21234"` |
| `6E2001` | `"6E2001"` |
| `BA5A` | `"BA5A"` |

It is stored in 3 columns, each named for the field, `_` and its suffix. This is `6E2001`:

| Column | Type | Holds |
|---|---|---|
| `<field>_airline` | `text` | `'6E'` |
| `<field>_number` | `integer` | `2001` |
| `<field>_suffix` | `text` | `NULL::text` |

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `BA123` | `BA123` |
| `U21234` | `U21234` |
| `6E2001` | `6E2001` |
| `BA5A` | `BA5A` |

## 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.