# `Slug`

A URL-safe name: lower-case words joined by hyphens, `autumn-sale`.

Use it for readable addresses, such as a blog post's. `text.slug` makes one from a title. For a login name, use [`Username`](/docs/types/type-username.md).

## Shape

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

## Example

```jadpo
Slug("autumn-sale")
```

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

`text.parse(raw, as: Slug)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `Spring-Collection`, `spring--collection` or `-spring`.

## Good to know

- Capitals and double hyphens are refused. `text.slug` tidies text so it fits.
- `==` 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
"spring-collection"
"2026-autumn-sale"
"a"
```

## Details

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

`Slug` is in the group Web and network, 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: `spring-collection`, `2026-autumn-sale` and `a`.

### How it is stored

It is stored in one column named for the field, of type `text`. `2026-autumn-sale` is stored as `'2026-autumn-sale'`.

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `spring-collection` | `spring-collection` |
| `2026-autumn-sale` | `2026-autumn-sale` |
| `a` | `a` |

### 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>