mapUUID (items) {
    return items.map((result, index) => {
      this.files[index].path = result !== undefined ? result : false
      return result && setId(result, this.files[index].uuid)
    })
  }
Run setId on each item of a pre-existing array of items.
@param {array} items expects an array of objects [{ url: '/uploads/file.pdf' }]