Please try to answer the following questions (when in doubt, have a look at the content in the chapter itself—you'll find all the answers there!):

1. In a Cloud Firestore database, what's the difference between a document and a collection? And can a document contain a collection?
2. Can you name three of the main differences between a SQL and a NoSQL database?
3. Consider the following code:

 docs = await db.collection('favourites')
.where('userId', isEqualTo: uid).getDocuments();

            What does this query perform? And which data type is the docs variable?

4. In a Cloud Firestore database, is it possible to allow data access only to authenticated users? If so, how can you achieve that?
5. How can you create an instance of a FirebaseAuth class?
6. Consider the following code:

var result = db.collection('favourites').add(fav.toMap()
    .then((value) => print(value.documentID))
    .catchError((error)=> print (error));

            Can you explain what these instructions perform?

7. When would you create a getter method for a property in a class? And how do you write the code to create it?
8. When do you need a Map object to interact with a Cloud Firestore database?
9. How do you delete a document from a Cloud Firestore database?
10. How do you pass data from one screen to another?