Query limitations and workarounds in Firebase - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Firestore query that filters documents where the field 'status' equals 'active'.

Firebase

db.collection('users').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 a wrong status value like 'inactive' or 'pending'.

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

2fill in blank

medium

Complete the code to order Firestore query results by the 'createdAt' timestamp in descending order.

Firebase

db.collection('posts').orderBy('createdAt', [1])

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

A'desc'

B'ascending'

C'asc'

D'descending'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'asc' which orders from oldest to newest.

Using 'desc' orders the results from newest to oldest based on 'createdAt'.

3fill in blank

hard

Fix the error in the Firestore query that tries to filter by two different fields without an index.

Firebase

db.collection('orders').where('status', '==', 'shipped').where('[1]', '==', 'priority')

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

Apriority

Bcustomer

Cdate

Damount

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field name that does not match the filter value.

The query filters orders where 'status' is 'shipped' and 'priority' is 'priority'. This requires a composite index on 'status' and 'priority'.

4fill in blank

hard

Fill both blanks to create a Firestore query that limits results to 10 and starts after a given document snapshot.

Firebase

db.collection('messages').orderBy('timestamp').[1](10).[2](lastVisible)

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

Alimit

BstartAfter

CendBefore

Doffset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'endBefore' or 'offset' which do not fit this pagination pattern.

The query limits results to 10 documents and starts after the last visible document for pagination.

5fill in blank

hard

Fill all three blanks to create a Firestore query that filters by 'category', orders by 'price', and limits to 5 results.

Firebase

db.collection('products').where('category', '==', [1]).orderBy([2]).[3](5)

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

A'electronics'

B'price'

Climit

D'name'

Attempts:

3 left

💡 Hint

Common Mistakes

Ordering by 'name' instead of 'price' or missing the limit method.

The query filters products in the 'electronics' category, orders them by 'price', and limits the results to 5.