# FileUpload

> File picker with size validation and clear control.

- Status: stable
- Group: form
- Page: https://www.digitaltableteur.com/design-system/components/file-upload
- Contract: https://www.digitaltableteur.com/contracts/v1/FileUpload.contract.json

## When to use

FileUpload is the single-file picker: a readonly summary field showing "name (size)" plus Browse and Clear buttons driving a hidden native input. It enforces maxSizeInBytes client-side (rejects, clears, and shows a localized error) and filters the picker via accept. Two appearances: default (TextInput + Button) and editorial (Combobox-style field for editorial forms).

## When not to use

- Do not render two FileUploads in the same form without unique labels. The labels disambiguate the AT context; identical labels collide.
- Do not rely on `value` for "the file is already on the server". FileUpload is for *selection*, not display of an already-uploaded asset. Render an uploaded asset as Link + Clear control instead.
- Do not skip the Clear button. Users who picked the wrong file have no recovery path without it on mobile (the platform sheet doesn't expose a "clear" affordance once a file is bound).
- Do not use value to represent an already-uploaded server file; it only mirrors a local File object.
- Do not use it for multi-file needs; it holds exactly one file (last pick wins).

## Look-alikes

The contract names no look-alike with a deciding condition.

## Props

| Prop | Type | Default | Description | Required |
| --- | --- | --- | --- | --- |
| `label` | `string` | none | Field label. | Yes |
| `placeholder` | `string` | none | Placeholder shown when no file is selected. | No |
| `helperText` | `string` | none | Helper copy below the control. | No |
| `uploadButtonLabel` | `string` | none | Upload button label. | Yes |
| `clearButtonLabel` | `string` | none | Clear/remove button label; the button shows only while a file is set, and activating it moves focus to the upload button. | No |
| `accept` | `string` | none | Accepted file extensions/MIME types for the native picker. | No |
| `maxSizeInBytes` | `number` | none | Maximum file size in bytes; checked when a file is picked. | No |
| `sizeErrorMessage` | `string` | none | Error shown when a picked file exceeds maxSizeInBytes. | No |
| `error` | `string` | none | External error message; renders above the helper line. | No |
| `value` | `File \| null` | `null` | Controlled File value. | No |
| `onFileChange` | `(file: File \| null) => void` | none | Called when a file is selected or cleared. | No |
| `disabled` | `boolean` | `false` | Disables the control. | No |
| `required` | `boolean` | `false` | Marks the field required. | No |
| `appearance` | `"default" \| "editorial"` | `default` | Match FormFieldEditorial / Combobox styling on editorial forms. | No |
| `className` | `string` | none | No description in the contract. | No |

## Variants

- Allowed `appearance` values: `default`, `editorial` (default `default`).

## Invalid combinations

The contract records no invalid combinations.

## Keyboard

| Key | Behaviour |
| --- | --- |
| Tab | Moves focus to the control and on to the next focusable element. (standard) |
| Enter | Activates the focused control. (standard) |
| Space | Activates or toggles the focused control. (standard) |

Rows marked (standard) name a key the contract lists without a description; the behaviour shown is the usual one for that key.

## Rules

Every item under When not to use is a MUST NOT. MUST and SHOULD follow RFC 2119.

| Level | Rule | How it is checked |
| --- | --- | --- |
| MUST | ARIA: Label association. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Error via an error HelperText (role=alert), announced once when it appears. Both appearances reference the error and then the helper text from the control with aria-describedby and set aria-invalid while an error shows. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Clear moves focus to the upload button before it unmounts, so focus never drops to the page body. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: With required, the editorial label adds an asterisk (aria-hidden) and a translated sr-only hint (fieldRequiredHint, English fallback "required") | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | Required stories produce no axe violations at the configured severity. | Automated by `npm run test:stories:matrix:ci`. WCAG 2.5.8. |
| MUST | The accessibility tree (role, name, state) matches the committed snapshot for every required story. | Automated by `npm run test:stories:matrix:ci`. WCAG 1.3.1, 4.1.2. |
| MUST | The component remains legible and operable under a real browser forced-colors: active pass. | Automated by `npm run test:stories:hc`. |
| MUST | Every documented keyboard interaction works as specified. | Not yet verified: no evidence record. WCAG 2.1.1, 2.1.2. |
| MUST | A human completed an end-to-end accessibility review of this component. | Manual review, last on 2026-11-04. |
| SHOULD | Always set accept and maxSizeInBytes; a picker without limits fails at the server instead of at the field. | Not stated in the contract. |
| SHOULD | Pass clearButtonLabel so users can undo a wrong pick without re-opening the OS dialog. | Not stated in the contract. |
| SHOULD | State the accepted formats and size cap in helperText; the accept filter is invisible until the dialog opens. | Not stated in the contract. |
| SHOULD | Treat onFileChange(null) as "cleared": reset your form state and any pending upload. | Not stated in the contract. |
| SHOULD NOT | Do not rely on the size check as security; it is UX-only and must be re-validated server-side. | Not stated in the contract. |

## Install and import

- Install: `npm install @digitaltableteur/react` (version 0.9.1, restricted access on npm).
- Import: `import { FileUpload } from "@digitaltableteur/react";`
- Entry point: `@digitaltableteur/react/forms` exports it too.
- Styles: import `@digitaltableteur/react/style.css` once at the app boundary.
- Also available as the custom element `<dt-file-upload>`; see the custom elements manifest.

## Links

- Machine-readable contract (Design System Contract 1.0): https://www.digitaltableteur.com/contracts/v1/FileUpload.contract.json
- Markdown version of this page: https://www.digitaltableteur.com/design-system/components/file-upload.md
- Component index as JSON: https://www.digitaltableteur.com/design-system/components.json
- All components: https://www.digitaltableteur.com/design-system/components
- Source: The implementation lives in a private repository. This page, its Markdown twin and the contract are generated from it at build time and are the public source of truth.