Array update with $[] all positional in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to update all elements in the array field 'scores' by setting them to 100.

MongoDB

db.students.updateMany({}, { $set: { "scores[1]": 100 } })

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

A.$[]

B.$

C.[0]

D.$[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using .$ instead of .$[] updates only the first element.

Using array index like [0] updates only one element.

The $[] operator updates all elements in the array.

2fill in blank

medium

Complete the code to increment all elements in the 'grades' array by 5.

MongoDB

db.courses.updateMany({}, { $inc: { "grades[1]": 5 } })

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

A.$[1]

B.$[]

C.$

D.[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using .$ increments only the first element.

Using an index like [0] increments only one element.

The $[] operator targets all elements in the array for the increment.

3fill in blank

hard

Fix the error in the code to set all elements in 'ratings' array to 5.

MongoDB

db.products.updateMany({}, { $set: { "ratings[1]": 5 } })

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

A.[0]

B.$[elem]

C.$[]

D.$

Attempts:

3 left

💡 Hint

Common Mistakes

Using .$ updates only the first element, not all.

Using array index updates only one element.

Using $[] updates all elements; .$ updates only the first.

4fill in blank

hard

Fill both blanks to multiply all elements in 'values' array by 2.

MongoDB

db.data.updateMany({}, { $mul: { "values[1]": [2] } })

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A.$[]

B2

C3

D.$

Attempts:

3 left

💡 Hint

Common Mistakes

Using .$ updates only the first element.

Multiplying by 3 instead of 2 changes the result.

The $[] operator targets all array elements, and $mul multiplies by the given number.

5fill in blank

hard

Fill both blanks to add 10 to all elements in 'scores' array and set 'updated' to true.

MongoDB

db.records.updateMany({}, { $inc: { "scores[1]": [2] }, $set: { "updated": true } })

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

A.$[]

B10

D.$

Attempts:

3 left

💡 Hint

Common Mistakes

Using .$ instead of .$[] updates only one element.

Adding wrong number instead of 10.

Using array operator on 'updated' field which is not an array.

$[] updates all array elements, $inc adds 10, and $set sets the 'updated' field (no array operator needed).