# `TrackingNumber`

A parcel's tracking number, with its carrier: `UPSN 1Z999AA10123456784`.

Use it to track a parcel with a courier. For a pallet, use [`Sscc`](/docs/types/type-sscc.md). For a sea container, use [`ContainerNumber`](/docs/types/type-container-number.md).

## Shape

| Field | Type | Required? |
|---|---|---|
| `carrier` | [`Carrier`](/docs/types/type-carrier.md) | Yes |
| `number` | `Text` | Yes |

## Example

```jadpo
TrackingNumber { carrier: "UPSN" number: "1Z999AA10123456784" }
```

`text.parse(raw, as: TrackingNumber)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `upsn 1Z999AA10123456784`, `UPSN 1z999aa10123456784` or `UPSN  1Z999AA10123456784`.

## Good to know

- The number is in capitals, as carriers print it.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it, so sort by one of its parts instead.

## In JSON

A string, in a request, a response or `json.write`:

```json
"UPSN 1Z999AA10123456784"
"FDXE 449044304137821"
"USPS 9400111899223197428490"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`TrackingNumber` is in the group Commerce and logistics, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `UPSN 1Z999AA10123456784`, `FDXE 449044304137821` and `USPS 9400111899223197428490`.

### How it is stored

It is stored in 2 columns, each named for the field, `_` and its suffix. This is `FDXE 449044304137821`:

| Column | Type | Holds |
|---|---|---|
| `<field>_carrier` | `text` | `'FDXE'` |
| `<field>_number` | `text` | `'449044304137821'` |

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `UPSN 1Z999AA10123456784` | `UPSN 1Z999AA10123456784` |
| `FDXE 449044304137821` | `FDXE 449044304137821` |
| `USPS 9400111899223197428490` | `USPS 9400111899223197428490` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>