Expected first argument to collection() to be a collectionreference, a documentreference or firebasefirestore

The Firestore error “Expected first argument to collection() to be a CollectionReference, a DocumentReference, or FirebaseFirestore” occurs when the provided argument to the collection() method is invalid or does not meet the required format.

In Firestore, the collection() method is used to access a collection of documents within a specific database. The first argument passed to the collection() method should be a valid reference to a collection, document, or the entire Firestore instance.

Here are some examples of correct usage and explanations for each case:

1. Collection Reference

If you want to access a specific collection within your Firestore database, you need to pass a valid reference to that collection. The reference should be obtained using the collection() method of a Firestore instance or another collection reference.

    
const firestore = firebase.firestore();
const collectionRef = firestore.collection('myCollection');
    
  

2. Document Reference

If you want to access a specific document within a collection, you need to pass a valid reference to that document. The reference should be obtained using the doc() method of a collection reference or a Firestore instance.

    
const firestore = firebase.firestore();
const collectionRef = firestore.collection('myCollection');
const documentRef = collectionRef.doc('myDocument');
    
  

3. Firestore Instance

If you want to access the entire Firestore instance, you can simply use the firestore() method without any arguments.

    
const firestore = firebase.firestore();
    
  

Make sure to check that the argument you are passing to the collection() method is one of these valid references, and that it is not an empty or undefined value. This should help resolve the Firestore error mentioned above.