Need help with dropdown and creating new documents

Hello

Ive building flutterflow app with Firebase database

Got two collections in Firebase:

One is CarDocument:

NameCarDocument: string

filepathCarDocument: string

Producer: Doc Reference: Producer

Then I got Producer:

NameProducer: string

There are different Documents in Producer Collections like:

Audi, BMW, VW, Fiat

What im trying to do is build a page when I could using Backend Call Create new documents in CarDocument collection using dropdown to choose correct Producer:

So ive got:

Textfield: for NameCarDocument - works ok

Action Button to upload document to firebase and have filepathCarDocument - works ok

and there is a problem:

would like to have dropdown with Producer collection so (Audi, BMW, VW, Fiat) - I can do it by Query Collection of Producer by then I could not set the Dropdown value into Producer: Doc Reference: Producer field.

I could then again Query Collection of Producer filtering by output of the Dropdown to get proper Producer Ref - but its very ugly solution and when I got more drop-down I got a lot of Querying and filtering,

What is the proper solution to send Producer Ref of chosen NameProducer in dropdown to create new document (CarDocument)?

Thx for help

Greetings

5hinka