The edit API is called in the view using a fetch method that takes the form data and sends the multipart request to the backend.
mern-marketplace/client/shop/api-shop.js:
const update = (params, credentials, shop) => { return fetch('/api/shops/' + params.shopId, { method: 'PUT', headers: { 'Accept': 'application/json', 'Authorization': 'Bearer ' + credentials.t }, body: shop }).then((response) => { return response.json() }).catch((err) => { console.log(err) })}