Why compound queries narrow results in Firebase - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to query 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'pending'

C'active'

D'deleted'

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a status that does not match the intended filter.

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

2fill in blank

medium

Complete the code to add a second condition to the query to filter users with age greater than 18.

Firebase

db.collection('users').where('status', '==', 'active').where('age', [1], 18)

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

A<=

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' or '<' which select younger users.

The query filters users older than 18 by using the '>' operator.

3fill in blank

hard

Fix the error in the compound query that tries to filter by 'status' and 'age' but uses an invalid operator.

Firebase

db.collection('users').where('status', '==', 'active').where('age', [1], 18)

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

A>

Barray-contains

C!=

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'array-contains' or 'in' with numeric fields.

The '>' operator is valid for numeric comparisons like age. 'array-contains' and 'in' are for arrays or lists, not numbers.

4fill in blank

hard

Fill both blanks to create a compound query filtering users with 'status' 'active' and 'score' greater than 50.

Firebase

db.collection('users').where('status', [1], [2]).where('score', '>', 50)

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

A'=='

B'active'

C'inactive'

D'pending'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong operator or status value.

The first condition checks if 'status' equals 'active'.

5fill in blank

hard

Fill all three blanks to create a compound query filtering users with 'status' 'active', 'score' greater than 50, and 'age' less than 30.

Firebase

db.collection('users').where('status', [1], [2]).where('score', '>', 50).where('age', [3], 30)

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

A'=='

B'active'

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong operators for age or status.

The query filters users with status 'active', score greater than 50, and age less than 30.