file

A file from <input type="file"> or FormData: size and type.

Signature

function file(options?: { maxSize?: number; types?: string[] }, msg?: Message): Schema<File>

Parameters

Parameter	Type	Description
options.maxSize	number	Maximum size in bytes: 2 * 1024 * 1024
options.types	string[]	MIME types, groups and extensions: ['image/*', 'application/pdf', '.docx']
msg	Message	Custom message for all file errors

Error codes

Code	When	Default message
required	The value is empty and the field is required	Required
file	Not a file	Must be a file
fileSize	The file is larger than maxSize	File must be at most {max}
fileType	The type is not in the list	File type must be one of: {types}

You can change the texts: see Messages & i18n.

Notes

• Works in the browser and in Node 20+ — there File comes from FormData (request.formData() in fetch, Hono, Nuxt).
• In the message {max} is a readable size: 2 MB. The error params also have size — the file size.
• Extensions are case-insensitive: .pdf accepts DOC.PDF.
• Several files — array with maxLength.

Examples

Avatar

const avatar = file({ maxSize: 2 * 1024 * 1024, types: ['image/*'] });

Several documents

const Application = object({
  documents: pipe(array(file({ types: ['application/pdf', '.docx'] })), minLength(1), maxLength(5)),
});

On the server

app.post('/upload', async (c) => {
  const form = Object.fromEntries(await c.req.formData());
  const { avatar } = parse(object({ avatar: file({ maxSize: 2 * 1024 * 1024 }) }), form);
});

See also

• array
• maxLength