Passing variable into Firestore document path

Question

I am trying to reference a variable that I am storing the users UID to in a document reference to Cloud Firestore. The path doesn't seem to read a string though. I have tried two different way and both ways give me errors. How would you pass a variable string into a Cloud Firestore document/collection path?

I am getting the UsernameID from the database with:

UsernameID = Auth.auth().currentUser!.uid

var UsernameID = String()

let ref = db.collection("user/\(UsernameID)/account").document("created")
        ref.getDocument { (document, error) in
            if let document = document, document.exists {
                print("User Exists")
            } else {
                print("User does not exist in firestore")
            }
        }

Throws error:

*** Terminating app due to uncaught exception 'FIRInvalidArgumentException', reason: 'Invalid path (user//account). Paths must not contain // in them.'
libc++abi.dylib: terminating with uncaught exception of type NSException

var UsernameID = String()

let ref = db.collection("user").document(UsernameID).collection("account").document("created")
        ref.getDocument { (document, error) in
            if let document = document, document.exists {
                print("User Exists")
            } else {
                print("User does not exist in firestore")
            }
        }

Throws error:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'FIRESTORE INTERNAL ASSERTION FAILED: Invalid document reference. Document references must have an even number of segments, but user has 1'

I have also tried storing the uid as a DocumentReferce but it failed to store a string as a DocumentReference.

let UsernameID = DocumentReference!

It looks like your code is passing an empty string as the id of a document. That's never going to work. — Doug Stevenson

Jay Jay · Accepted Answer · 2019-07-06T14:15:25

Assuming you are authenticating correctly, here's what you want to do to access a document stored in Firestore. Suppose the structure is

users //collection
   uid //document
      name //field within the document

and the code to read the name field

let uid = Auth.auth().currentUser?.uid
let collectionRef = self.db.collection("users")
let userDoc = collectionRef.document(uid)
userDoc.getDocument(completion: { document, error in
     if let err = error {
         print(err.localizedDescription) //document did not exist
         return
     }

     if let doc = document {
         let name = doc.get("name")
         print(name)
     }
 })

Passing variable into Firestore document path

2 Answers