Querying array elements directly in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find documents where the array 'tags' contains the value 'mongodb'.

MongoDB

db.collection.find({ tags: [1] })

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

A"tags"

B{ "$in": ["mongodb"] }

C{ "$all": ["mongodb"] }

D"mongodb"

Attempts:

3 left

💡 Hint

Common Mistakes

Using $in or $all unnecessarily when a direct match works.

Quoting the field name instead of the value.

To find documents where the array 'tags' contains 'mongodb', you directly match the value with the field name.

2fill in blank

medium

Complete the code to find documents where the 'scores' array contains the number 85.

MongoDB

db.collection.find({ scores: [1] })

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

A{ "$elemMatch": { "$eq": 85 } }

B85

C"85"

D{ "$in": [85] }

Attempts:

3 left

💡 Hint

Common Mistakes

Quoting numbers as strings.

Using $elemMatch unnecessarily for a simple value.

To find documents where the array contains the number 85, you can directly match the number without quotes.

3fill in blank

hard

Fix the error in the query to find documents where the 'items' array contains the string 'book'.

MongoDB

db.collection.find({ items: [1] })

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

A"book"

Bbook

C{ "$eq": "book" }

D{ "$in": "book" }

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving string values unquoted.

Using $in with a string instead of an array.

The value 'book' must be a string in quotes to match array elements correctly.

4fill in blank

hard

Fill both blanks to find documents where the 'ratings' array contains a value greater than 4.

MongoDB

db.collection.find({ ratings: { [1]: [2] } })

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

A"$gt"

B4

C5

D"$lt"

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt instead of $gt.

Using a value other than 4.

Use the $gt operator with the value 4 to find array elements greater than 4.

5fill in blank

hard

Fill all three blanks to find documents where the 'comments' array contains an element with 'author' equal to 'Alice' and 'likes' greater than 10.

MongoDB

db.collection.find({ comments: { [1]: { [2]: "Alice", [3]: 10 } } })

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

A"$elemMatch"

B"author"

C"likes"

D"$gt"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using $elemMatch for multiple conditions.

Mixing up field names or operators.

Use $elemMatch to match array elements with multiple conditions: author equals 'Alice' and likes greater than 10.