# `ContainerNumber`

A shipping container's number, checked by its check digit: `CSQU3054383`.

Use it for sea and rail freight containers. For a parcel, use [`TrackingNumber`](/docs/types/type-tracking-number.md). For a software container, use [`ContainerImage`](/docs/types/type-container-image.md).

## Shape

One value, held as text in one set form, with no parts: `TOLU4734787`.

## Example

```jadpo
ContainerNumber("CSQU3054383")
```

`ContainerNumber(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: ContainerNumber)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `CSQU3054384`, `CSQA3054383` or `CSQU 305438 3`.

## Good to know

- Write it with no spaces. `text.format` adds them: `CSQU 305438 3`.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.

## In JSON

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

```json
"CSQU3054383"
"MSKU9070323"
"TOLU4734787"
```

## Details

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

`ContainerNumber` 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: `CSQU3054383`, `MSKU9070323` and `TOLU4734787`.

### How it is stored

It is stored in one column named for the field, of type `text`. `MSKU9070323` is stored as `'MSKU9070323'`.

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `CSQU3054383` | `CSQU 305438 3` |
| `MSKU9070323` | `MSKU 907032 3` |
| `TOLU4734787` | `TOLU 473478 7` |

### 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>