# `ShoeSize`

A shoe size in its system, as the box writes it: `UK 7.5`, `EU 42`.

Use it for shoes in a shop. For clothes, use [`ClothingSize`](/docs/types/type-clothing-size.md).

## Shape

| Field | Type | Required? |
|---|---|---|
| `system` | [`ShoeSizeSystem`](/docs/types/type-shoe-size-system.md) | Yes |
| `size` | `Text` | Yes |

## Example

```jadpo
ShoeSize { system: ShoeSizeSystem.uk size: "7.5" }
```

`text.parse(raw, as: ShoeSize)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `UK 7,5`, `UK 7.25` or `UK 07`.

## Good to know

- A half size is written with a point, `7.5`. `7,5` and `7.25` are refused.
- `==` 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
"UK 7.5"
"EU 42"
"US 9"
```

## Details

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

`ShoeSize` 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: `UK 7.5`, `EU 42` and `US 9`.

### How it is stored

It is stored in 2 columns, each named for the field, `_` and its suffix. This is `US 9`:

| Column | Type | Holds |
|---|---|---|
| `<field>_system` | `text` | `'US'` |
| `<field>_size` | `text` | `'9'` |

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `UK 7.5` | `UK 7.5` |
| `EU 42` | `EU 42` |
| `US 9` | `US 9` |
| `EU 38.5` | `EU 38.5` |

### 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>