Date and timestamp types in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new Date object representing the current date and time.

MongoDB

const currentDate = new [1]();

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

AISODate

BTimestamp

CDate

DTime

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Timestamp' instead of 'Date' to create a date object.

Using 'ISODate' which is a helper but not the standard Date constructor.

The Date object in MongoDB JavaScript represents date and time. Using new Date() creates the current date and time.

2fill in blank

medium

Complete the code to insert a document with a field 'createdAt' set to the current date and time.

MongoDB

db.collection.insertOne({ createdAt: [1] });

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

ATimestamp()

Bnew Date()

CISODate()

DDate()

Attempts:

3 left

💡 Hint

Common Mistakes

Using Date() without 'new' which returns a string, not a Date object.

Using Timestamp() which is a different type.

To store the current date and time in a document, use new Date(). This creates a Date object representing now.

3fill in blank

hard

Fix the error in the query to find documents with a 'createdAt' date greater than January 1, 2023.

MongoDB

db.collection.find({ createdAt: { $gt: [1] } })

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

Anew Date('2023-01-01')

BTimestamp('2023-01-01')

CISODate('2023-01-01')

D'2023-01-01'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a Date object causes no matches or errors.

Using 'Timestamp' incorrectly as it requires different parameters.

The $gt operator compares dates. You must provide a Date object. new Date('2023-01-01') creates a valid Date object for comparison.

4fill in blank

hard

Fill both blanks to create a query that finds documents with a 'lastModified' timestamp less than or equal to the current time.

MongoDB

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

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

A$lte

Bnew Date()

C$lt

DTimestamp()

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt instead of $lte changes the condition.

Using Timestamp() without 'new' or parameters is incorrect.

The operator $lte means 'less than or equal to'. Using new Date() gives the current date and time for comparison.

5fill in blank

hard

Fill all three blanks to create an update that sets the 'updatedAt' field to the current date and increments a 'version' field by 1.

MongoDB

db.collection.updateOne({ _id: id }, { [1]: { updatedAt: [2] }, [3]: { version: 1 } })

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

A$set

Bnew Date()

C$inc

D$currentDate

Attempts:

3 left

💡 Hint

Common Mistakes

Using $currentDate instead of $set with new Date().

Forgetting to increment the version field properly.

$set updates fields to specific values, here setting updatedAt to the current date with new Date(). $inc increments the version field by 1.

Practice

1. Which MongoDB data type is best for storing a human-readable date and time?

easy

A. Number

B. ISODate

C. String

D. Timestamp

Solution

1. Step 1: Understand MongoDB date types

   ISODate stores dates in a readable and standard format, suitable for queries and sorting.

2. Step 2: Compare with other types

   Timestamp is mainly for internal use, String and Number do not store dates natively.

3. Final Answer:

   ISODate -> Option B

4. Quick Check:

   Date type for readable time = ISODate [OK]

Hint: Use ISODate for readable and queryable dates [OK]

Common Mistakes:

• Confusing Timestamp with ISODate
• Using String to store dates
• Using Number for date storage

2. Which of the following is the correct way to create a date object for January 1, 2023 in MongoDB shell?

easy

A. Timestamp("2023-01-01")

B. new Date(2023-01-01)

C. ISODate("2023-01-01")

D. Date("2023-01-01")

Solution

1. Step 1: Recall MongoDB date creation syntax

   ISODate() is the correct function to create a date object in MongoDB shell.

2. Step 2: Check other options

   new Date() is JavaScript syntax but not recommended in MongoDB shell; Timestamp() is for internal timestamps; Date() returns string, not date object.

3. Final Answer:

   ISODate("2023-01-01") -> Option C

4. Quick Check:

   MongoDB date object = ISODate() [OK]

Hint: Use ISODate() to create dates in MongoDB shell [OK]

Common Mistakes:

• Using new Date() instead of ISODate()
• Using Timestamp() for normal dates
• Calling Date() without new keyword

3. Given the following MongoDB document:

{ "event": "meeting", "time": ISODate("2024-06-15T10:00:00Z") }

What will be the result of this query?

db.events.find({ time: { $gt: ISODate("2024-06-01T00:00:00Z") } })

medium

A. Returns documents with time after June 1, 2024

B. Returns documents with time before June 1, 2024

C. Returns all documents regardless of time

D. Syntax error in query

Solution

1. Step 1: Understand the query filter

   The query uses $gt (greater than) to find documents where time is after June 1, 2024.

2. Step 2: Check document time value

   The document time is June 15, 2024, which is after June 1, 2024, so it matches the filter.

3. Final Answer:

   Returns documents with time after June 1, 2024 -> Option A

4. Quick Check:

   $gt filter returns later dates [OK]

Hint: Use $gt to find dates after a given date [OK]

Common Mistakes:

• Confusing $gt with $lt
• Expecting syntax error
• Thinking it returns all documents

4. What is wrong with this MongoDB query to find documents with a timestamp field after a certain date?

db.logs.find({ timestamp: { $gt: "2024-01-01T00:00:00Z" } })

medium

A. The $gt operator is invalid

B. The query syntax is correct

C. The field name 'timestamp' is reserved

D. The date string should be wrapped in ISODate()

Solution

1. Step 1: Check the query filter value type

   The query compares the timestamp field to a string, but MongoDB expects a Date object for date comparisons.

2. Step 2: Correct the date format

   Wrapping the date string in ISODate() converts it to a Date object, making the query valid.

3. Final Answer:

   The date string should be wrapped in ISODate() -> Option D

4. Quick Check:

   Date comparisons need ISODate() objects [OK]

Hint: Wrap date strings with ISODate() for date queries [OK]

Common Mistakes:

• Using plain strings for date comparison
• Assuming $gt is invalid
• Thinking field names are reserved

5. You want to store user login times and also track the exact order of logins including multiple logins in the same second. Which MongoDB data type combination should you use?

hard

A. Use ISODate for login time and Timestamp for order tracking

B. Use only ISODate for both time and order

C. Use Timestamp for login time and String for order

D. Use String for both login time and order

Solution

1. Step 1: Understand the use of ISODate and Timestamp

   ISODate stores readable date/time; Timestamp is precise and used internally to track order of operations.

2. Step 2: Apply to login tracking

   Use ISODate to record when login happened, and Timestamp to track exact order if multiple logins occur at the same second.

3. Final Answer:

   Use ISODate for login time and Timestamp for order tracking -> Option A

4. Quick Check:

   ISODate for time + Timestamp for order = correct [OK]

Hint: Combine ISODate and Timestamp for time and order tracking [OK]

Common Mistakes:

• Using only ISODate loses order precision
• Using Timestamp for readable time
• Using strings instead of date types