String expressions ($concat, $toUpper, $toLower) in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to concatenate first and last names with a space in between.

MongoDB

{ $concat: ["$firstName", [1], "$lastName"] }

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

A" "

B"-"

C"_"

D","

Attempts:

3 left

💡 Hint

Common Mistakes

Using a dash or underscore instead of a space

Forgetting to put quotes around the space

We use a space " " to separate first and last names when concatenating.

2fill in blank

medium

Complete the code to convert the 'city' field to uppercase.

MongoDB

{ $toUpper: "$[1]" }

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

Acity

BCity

CCITY

DcitY

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase field names

Adding extra spaces inside the field name string

Field names are case-sensitive and usually lowercase; use "$city" to refer to the field.

3fill in blank

hard

Fix the error in the code to convert 'country' field to lowercase.

MongoDB

{ $toLower: "$[1]" }

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

ACountry

Bcountry

CCOUNTRY

DcOUNTRY

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase or mixed case field names

Adding spaces inside the field name string

The field name must match exactly, so use "$country" in lowercase.

4fill in blank

hard

Fill both blanks to concatenate first name and last name in uppercase with a space in between.

MongoDB

{ $concat: [ { $toUpper: "$firstName" }, [1], { $toUpper: "$lastName" } ] }

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

A","

B"-"

C"_"

D" "

Attempts:

3 left

💡 Hint

Common Mistakes

Using a dash or underscore instead of a space

Forgetting to put quotes around the space

We use a space " " to separate the uppercase first and last names when concatenating.

5fill in blank

hard

Fill all three blanks to concatenate lowercase city and uppercase country with a comma and space in between.

MongoDB

{ $concat: [ { $toLower: "$[1]" }, [2], { $toUpper: "$[3]" } ] }

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

Acity

B", "

Ccountry

D" - "

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong field names

Using dash instead of comma separator

Forgetting quotes around separator

We convert city to lowercase, country to uppercase, and separate them with a comma and space ", ".