Why Firebase provides backend services in Flutter - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize Firebase in a Flutter app.

Flutter

await Firebase.[1]();

Drag options to blanks, or click blank then click option'

AstartApp

BinitializeApp

CrunApp

DlaunchApp

Attempts:

3 left

💡 Hint

Common Mistakes

Using runApp instead of initializeApp

Calling startApp which does not exist

Firebase apps start by calling initializeApp() to set up backend services.

2fill in blank

medium

Complete the code to add a document to Firestore database.

Flutter

FirebaseFirestore.instance.collection('users').[1]({'name': 'Anna'});

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Aadd

Bget

Cupdate

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using get which reads data

Using update which modifies existing data

The add() method adds a new document to a Firestore collection.

3fill in blank

hard

Fix the error in the code to listen for authentication state changes.

Flutter

FirebaseAuth.instance.authStateChanges().[1]((User? user) {
  if (user == null) {
    print('User signed out');
  } else {
    print('User signed in');
  }
});

Drag options to blanks, or click blank then click option'

AonChange

Bsubscribe

Clisten

Dwatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using subscribe which is not a Dart Stream method

Using onChange which does not exist

The listen() method subscribes to stream events like auth state changes.

4fill in blank

hard

Fill both blanks to create a map of user IDs to their email addresses from a list.

Flutter

var userMap = {user.[1]: user.[2] for user in users};

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Auid

Bemail

Cname

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using name or id which are not standard Firebase user properties

Each user object has a unique ID as uid and an email as email.

5fill in blank

hard

Fill all three blanks to filter and map Firestore documents with age over 18.

Flutter

var adults = {doc.[1]: doc.data()[[2]] for doc in snapshot.docs if doc.data()[[3]] > 18};

Drag options to blanks, or click blank then click option'

Aid

B'age'

C'name'

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up field names or using data instead of id for keys

Use id for document ID, 'name' for mapping, and filter by 'age' field.