Realtime Database in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the Firebase Realtime Database instance.

Flutter

final database = FirebaseDatabase.instance[1];

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

A.initialize()

B.connect()

C.start()

D.ref()

Attempts:

3 left

💡 Hint

Common Mistakes

Using .initialize() instead of .ref()

Trying to call .connect() which does not exist

The FirebaseDatabase.instance.ref() method gets a reference to the root of the database.

2fill in blank

medium

Complete the code to write data to the 'users' node in the database.

Flutter

database.ref('users').[1]({'name': 'Alice', 'age': 25});

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

Aget

Bupdate

Cset

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' which reads data instead of writing

Using 'remove' which deletes data

The set method writes data to the specified database reference, replacing any existing data.

3fill in blank

hard

Fix the error in the code to listen for realtime updates on the 'messages' node.

Flutter

database.ref('messages').on[1]((event) {
  final data = event.snapshot.value;
  print(data);
});

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

Avalue

Bchange

Cupdate

Dchild_added

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'onChange' which is not a valid event

Using 'onChildAdded' which listens only for new child nodes

The onValue event listens for any changes to the data at the reference and returns the snapshot.

4fill in blank

hard

Fill both blanks to update the 'status' field to 'online' for user with id 'user123'.

Flutter

database.ref('users/[1]').[2]({'status': 'online'});

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

Auser123

Bset

Cupdate

DuserId

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' which overwrites all data at the path

Using a variable name instead of the actual user ID string

Use the user ID 'user123' as the child path and update to change only the 'status' field without overwriting other data.

5fill in blank

hard

Fill all three blanks to remove the 'age' field from user 'user456'.

Flutter

database.ref('users/[1]').[2]({'[3]': null});

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

Auser456

Bupdate

Cage

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' which overwrites all data

Trying to remove the field by deleting the whole user node

To remove a field, update it with null. Use the user ID 'user456' and the update method to remove only the 'age' field.