# `RelativeUrl`

A relative reference (RFC 3986): a path, a query or a fragment, or a host after `//`, with no scheme: `../images/logo.png`, `?page=2`. `web.resolve` makes a `Url` of one.

[Web and network](types.md#web-and-network); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its text, `RelativeUrl("../images/logo.png")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: RelativeUrl)` reads one from its text; text that isn't one at all fails `malformed`, such as `https://example.com/`, `mailto:someone@example.com` or `a:b`.

## 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 |
|---|---|
| `../images/logo.png` | `"../images/logo.png"` |
| `/docs?page=2#intro` | `"/docs?page=2#intro"` |
| `//cdn.example.com/app.js` | `"//cdn.example.com/app.js"` |
| `?sort=name` | `"?sort=name"` |
| `#top` | `"#top"` |
| `caf%C3%A9.html` | `"caf%C3%A9.html"` |

It is stored in one column named for the field, of type `text`. `?sort=name` is stored as `'?sort=name'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `../images/logo.png` | `../images/logo.png` |
| `/docs?page=2#intro` | `/docs?page=2#intro` |
| `//cdn.example.com/app.js` | `//cdn.example.com/app.js` |
| `?sort=name` | `?sort=name` |
| `#top` | `#top` |
| `caf%C3%A9.html` | `caf%C3%A9.html` |

## Operations

- `web.resolve(base: Url, relative: RelativeUrl) -> Url`: `relative` resolved against `base` by RFC 3986 (section 5.2): its `.` and `..` segments followed, a path starting `/` taken from the host, a query or a fragment alone kept with the base's path. A `UrlPath` is a `RelativeUrl`, so it resolves too.

Like every standard type, it also 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.