Hidden Field (Form Integration)

Uploaded file GUIDs are automatically synced to a hidden input, ready for form submission.

new MultipleUpload('#demo', {
 uploadUrl: '/api/upload',
 multiple: true,
 hiddenFieldId: 'file-guids'
});

Submitting references instead of bytes

hiddenFieldId defaults to null. Point it at the id of a hidden input and the component keeps that input in sync with the queue: as each upload completes its GUID is appended, comma-separated. Your form then posts a short list of identifiers rather than any file content, so the submit stays instant no matter how much was uploaded.

What the server does with it

The GUIDs identify files your upload endpoint has already stored, so the form handler is doing bookkeeping rather than file handling — associating them with a record, moving them out of temporary storage, discarding the ones the user removed before submitting. A file whose upload never completed never gets a GUID and therefore never reaches the form.

Treat the field as untrusted, like any other form input. A GUID arriving in a POST proves only that someone typed it; check that it belongs to the current session before acting.