Array of embedded documents queries in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find documents where the array 'scores' contains an element with 'score' equal to 100.

MongoDB

db.students.find({"scores.score": [1])

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

A100

B"100"

Cscore

D{score: 100}

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string "100" instead of the number 100.

Trying to match the whole embedded document instead of just the score value.

The query matches documents where any element in the 'scores' array has a 'score' field equal to 100. The value should be a number, not a string or object.

2fill in blank

medium

Complete the code to find documents where the 'scores' array contains an element with 'type' equal to 'exam'.

MongoDB

db.students.find({"scores.type": [1])

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

Aexam

B"exam"

C'exam'

D{type: 'exam'}

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the string value, causing a syntax error.

Using single quotes without escaping inside JSON.

The value for 'type' is a string, so it must be enclosed in quotes in the query. Using double quotes inside the query is correct.

3fill in blank

hard

Fix the error in the query to find documents where the 'scores' array contains an element with 'score' greater than 90.

MongoDB

db.students.find({"scores.score": [1])

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

A{ $lt: 90 }

B{ gt: 90 }

C{ $gte: 90 }

D{ $gt: 90 }

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the '$' sign before 'gt'.

Using the wrong operator like '$lt' or 'gte' when 'gt' is needed.

The correct MongoDB operator for 'greater than' is '$gt'. It must be prefixed with a dollar sign.

4fill in blank

hard

Fill both blanks to find documents where the 'scores' array contains an element with 'type' equal to 'quiz' and 'score' less than 50.

MongoDB

db.students.find({"scores": { $elemMatch: {"type": [1], "score": [2] } } })

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

A"quiz"

B{ $lt: 50 }

C{ $gt: 50 }

D"exam"

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the string 'quiz'.

Using $gt instead of $lt for the score condition.

The $elemMatch operator matches array elements that satisfy both conditions: 'type' is the string "quiz" and 'score' is less than 50 using $lt.

5fill in blank

hard

Fill all three blanks to find documents where the 'scores' array contains an element with 'type' equal to 'homework', 'score' greater than or equal to 80, and 'score' less than 100.

MongoDB

db.students.find({"scores": { $elemMatch: {"type": [1], "score": [2], "score": [3] } } })

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

A"homework"

B{ $gte: 80 }

C{ $lt: 100 }

D"quiz"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same key 'score' twice without $elemMatch (which is invalid).

Not quoting the string 'homework'.

Using wrong operators like $gt instead of $gte.

The $elemMatch operator matches array elements where 'type' is "homework", 'score' is greater than or equal to 80 ($gte), and less than 100 ($lt).