# `FileName`

A file's name that every common file system takes: `report.pdf`.

Use it for a download's or an upload's name. For a whole path, use [`FilePath`](/docs/types/type-file-path.md).

## Shape

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

## Example

```jadpo
FileName("report.pdf")
```

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

`text.parse(raw, as: FileName)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `notes/today.txt`, `notes\today.txt` or `what?.txt`.

## Good to know

- It refuses `/`, `\` and Windows' reserved names, and goes up to 255 bytes. So a name from an upload can't reach another folder.
- `==` 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
"report.pdf"
"Résumé 2026.docx"
".gitignore"
```

## Details

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

`FileName` is in the group Software, 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: `report.pdf`, `Résumé 2026.docx` and `.gitignore`.

### How it is stored

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

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `report.pdf` | `report.pdf` |
| `Résumé 2026.docx` | `Résumé 2026.docx` |
| `.gitignore` | `.gitignore` |
| `archive.tar.gz` | `archive.tar.gz` |
| `CONSOLE.txt` | `CONSOLE.txt` |

### 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>