Can I update fields with the @id directive?

Sorry, I might be mistaken here but how would I get the input parameter if I don’t pass it to dql.mutate? I could do something like

{
  "uid": `${input.userId}`
  "email": `${input.email}`
  "role": {
    roleId: `${input.roleId}`
  }
}

but unfortunately this does not work either.