CODEWITHSUNDEEP
androidfirebasekotlingoogle-cloud-firestore
Pravin Sonawane
Pravin Sonawane

Reputation: 1833

How to query Firebase Firestore Reference data type?

I'm using the Firestore reference data type to store a reference to a User as shown in the screenshots below

User reference

enter image description here

Users collections

enter image description here

When I try to query this data, I get a ClassCastException (I tried to cast to a String just for the sake of it).

Code

//.. this function reads data from DocumentSnapshot
//.. and converts to an Organization
private fun DocumentSnapshot.toOrganization(): Organization {
  //.. some code
      (this.data["members"] as ArrayList<HashMap<String, Any>>).map { toOrgMember(it) })
  //.. more code
}

fun toOrgMember(map: Map<String, Any>): OrgMember {
  //map["user"] as String throws ClassCastException. Refer first screenshot
  return OrgMember(map["id"] as Long, UserRef(map["user"] as String), map["type"] as String,
      asJobTitlesList(map["jobTitles"] as String))
}

Stacktrace

10-14 20:31:17.503 15569-15569/com.a.b W/System.err: Caused by: java.lang.ClassCastException: com.google.android.gms.internal.zzegf cannot be cast to java.lang.String
10-14 20:31:17.504 15569-15569/com.a.b W/System.err:     at feature.model.core.CoreUtilsKt.toOrgMember(CoreUtils.kt:28)
10-14 20:31:17.504 15569-15569/com.a.b W/System.err:     at feature.model.organization.OrgRemoteKt.toOrganization(OrgRemote.kt:55)

To what class should I cast the reference data type? (com.google.android.gms.internal.zzegf seems like an internal class which shouldn't be used)

As of now, I didn't find any example in the docs for a reference type. Any help would be appreciated.

Upvotes: 6

Views: 8891

Answers (3)

Akajit Saelim
Akajit Saelim

Reputation: 91

I suffer same your problem. However I can solve this problem using:

DocumentReference docRef = firestore.document(map.get("reference_field").toString());

I'm not sure that this is correct way, but this way works for me.

-- Update --

It seems new firestore version (11.6.0) on android can't use my way. However it can be cast directly

DocumentReference docRef = (DocumentReference) map.get("reference_field");

Upvotes: 1

camendoza94
camendoza94

Reputation: 185

Firestore returns a DocumentReference when getting a reference from your collections. If changing the cast to DocumentReference doesn't work, keep track of this issue.

Upvotes: 3

Edward DiGirolamo
Edward DiGirolamo

Reputation: 762

We will need to see some of your code to give you an answer. but in the meantime here is what my query snippet looks like, it assumes you are looking for something unique if not you can loop through the results.

FireBaseFirestore db = FirebaseFirestore.getInstance();
collectionRef = db.collection("yourCollection");
Query query = collectionRef.whereEqualTo("Field", "yourQuery" );
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                        @Override
                        public void onComplete(@NonNull Task<QuerySnapshot> task) {
                            if(task.isSuccessful()) {
                                QuerySnapshot qSnap = task.getResult();
                                if (!qSnap.isEmpty()) {
                                    Log.d("Query Data", String.valueOf(task.getResult().getDocuments().get(0).getData()));                                       
                                } else {
                                    Log.d("Query Data", "Data is not valid");

                                }

                            }
                        }
                    });

Upvotes: 2

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