firestore: how to check if a document exist

Issue

I have a collection admins in my firestore, where i add document IDs of users with admin roles.

In other to grant users admin role, i need to check if their users ID (documentID) is found under admin collection.

here is my code:

isAdmin() async {
await getUser.then((user) async {
  final adminRef = await _db.collection("admins").doc(user?.uid).get();
  if (adminRef.exists) {
    admin.value = true;
  } else {
    admin.value = false;
  }
  update();
}); }

It keeps returning false where as the document of the current user exist under admins.

when i replace the collection in the query by users, it works fine.

i don’t know where i’m going wrong. any clue please?

here is admins collection image
image of admins collection

here is users collection image
image of users collection

Solution

This will work. data() method will return null if no document present and return {} when the blank / empty document present.

isAdmin() async {
await getUser.then((user) async {
  final adminRef = await _db.collection("admins").doc(user).get();
  if (adminRef.data() == {}) {
    admin.value = true;
  } else {
    admin.value = false;
  }
  update();
}); }

I didn’t get why you are creating empty documents inside the collection. Instead you can store the userId of admin in the each document and assign userId as a documentId. and you can check it by using where queries.

Answered By – Dhananjay Gavali

Answer Checked By – Candace Johnson (FlutterFixes Volunteer)

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