[cloud_firestore] See if a key and value exist in a map in an array in a field in a collection

[prawnydagrate]

My Cloud Firestore database is structured like this:

chats (collection)
  - xxxxxxxxx (field with id)
    - users: list<string>
    - messages: list<map<string, dynamic>>
      - 0
        - sender: string
        - body: string
        - timestamp: int
        - id: string
users (collection)
  ...

How do I look for a message throughout the whole chats collection with a certain id? Because each time a user sends a message, I need to generate an id for the message but also make sure that no other message has the exact same id.

[rrousselGit]

chats/id/messages probably should be a collection

Then you can do:

await app.doc('chats/id/messages/id2').exists