Collection group queries in Firebase - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a collection group query for all 'messages' collections.

Firebase

const query = firestore.collectionGroup('[1]');

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

Ausers

Bcomments

Cmessages

Dposts

Attempts:

3 left

💡 Hint

Common Mistakes

Using a top-level collection name instead of the subcollection name.

Misspelling the collection name.

The collectionGroup method queries all collections with the given name, here 'messages'.

2fill in blank

medium

Complete the code to add a filter where the 'status' field equals 'active' in the collection group query.

Firebase

const activeMessages = firestore.collectionGroup('messages').where('status', '==', [1]);

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

A'inactive'

B'active'

C'pending'

D'deleted'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong status string.

Forgetting quotes around the string value.

The where clause filters documents where the 'status' field is exactly 'active'.

3fill in blank

hard

Fix the error in the code by completing the method to get the query results.

Firebase

const snapshot = await firestore.collectionGroup('messages').[1]();

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

Aget

Bretrieve

Cload

Dfetch

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like 'fetch' or 'retrieve'.

Omitting the parentheses after the method name.

The get() method fetches the documents matching the query.

4fill in blank

hard

Fill both blanks to create a query that orders messages by 'timestamp' descending and limits to 10 results.

Firebase

const recentMessages = firestore.collectionGroup('messages').orderBy('[1]', '[2]').limit(10);

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

Atimestamp

Basc

Cdesc

DcreatedAt

Attempts:

3 left

💡 Hint

Common Mistakes

Using ascending order instead of descending.

Using the wrong field name for ordering.

Ordering by 'timestamp' descending shows newest messages first. The limit(10) restricts results to 10.

5fill in blank

hard

Fill all three blanks to create a query that filters messages with 'read' equal to false, orders by 'timestamp' ascending, and limits to 5 results.

Firebase

const unreadMessages = firestore.collectionGroup('[1]').where('[2]', '==', [3]).orderBy('timestamp', 'asc').limit(5);

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

Amessages

Bread

CFalse

DTrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'true' instead of 'false' for unread messages.

Using the wrong collection group name.

This query targets the 'messages' collection group, filters for unread messages where 'read' is false, orders by 'timestamp' ascending, and limits to 5 results.