BSON data types overview in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert a document with a string field in MongoDB.

MongoDB

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

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

Anull

B123

C"Alice"

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around string values.

Using numbers or booleans instead of strings.

The name field expects a string value, so we use quotes around the text.

2fill in blank

medium

Complete the code to insert a document with a boolean field in MongoDB.

MongoDB

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

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

A"true"

Btrue

C"false"

DFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around boolean values.

Using capitalized False instead of lowercase false.

The active field is a boolean, so we use the boolean value true without quotes.

3fill in blank

hard

Fix the error in the code to insert a document with a date field in MongoDB.

MongoDB

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

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

Anew Date()

B"new Date()"

CDate()

Ddate()

Attempts:

3 left

💡 Hint

Common Mistakes

Putting new Date() inside quotes, making it a string.

Using Date() without new, which returns a string.

To store a date in BSON, use new Date() which creates a Date object. Quoting it makes it a string, which is incorrect.

4fill in blank

hard

Fill both blanks to create a document with an ObjectId and a null field.

MongoDB

db.collection.insertOne({ _id: [1], deletedAt: [2] })

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

AObjectId()

Bnull

Cundefined

Dnew ObjectId()

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined instead of null.

Using new ObjectId() which is valid but not the preferred shorthand here.

The _id field uses ObjectId() to create a unique ID. The deletedAt field is set to null to show no deletion date.

5fill in blank

hard

Fill all three blanks to create a document with a binary data field, a decimal number, and an array.

MongoDB

db.collection.insertOne({ data: [1], price: [2], tags: [3] })

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

ABinData(0, "AQID")

BDecimal128("19.99")

C["sale", "new"]

DBuffer.from("AQID")

Attempts:

3 left

💡 Hint

Common Mistakes

Using Buffer.from which is Node.js specific, not BSON.

Using strings instead of arrays for tags.

BinData stores binary data in BSON. Decimal128 stores precise decimal numbers. Arrays are represented with square brackets.

Practice

1. Which BSON data type is used to store a unique identifier for documents in MongoDB?

easy

A. Date

B. String

C. ObjectId

D. Boolean

Solution

1. Step 1: Understand the purpose of ObjectId

   ObjectId is a special BSON type designed to uniquely identify documents in MongoDB collections.

2. Step 2: Compare with other types

   String stores text, Boolean stores true/false, Date stores time values. None of these uniquely identify documents like ObjectId.

3. Final Answer:

   ObjectId -> Option C

4. Quick Check:

   BSON unique ID = ObjectId [OK]

Hint: Unique document IDs in MongoDB are ObjectIds [OK]

Common Mistakes:

• Confusing String with ObjectId for unique IDs
• Thinking Boolean can identify documents
• Assuming Date stores unique identifiers

2. Which of the following is the correct BSON data type to store a true or false value in MongoDB?

easy

A. Integer

B. Boolean

C. String

D. Array

Solution

1. Step 1: Identify the BSON type for true/false

   Boolean is the BSON data type used to store true or false values.

2. Step 2: Eliminate other types

   Integer stores numbers, String stores text, Array stores lists. None represent true/false directly.

3. Final Answer:

   Boolean -> Option B

4. Quick Check:

   True/false = Boolean [OK]

Hint: True or false values use Boolean type [OK]

Common Mistakes:

• Using Integer for true/false
• Confusing String with Boolean
• Choosing Array for single true/false

3. Given the following MongoDB document:
{ "name": "Alice", "age": 30, "member": true }
What BSON data types are used for the fields name, age, and member respectively?

medium

A. String, Boolean, Integer

B. String, String, Boolean

C. ObjectId, Integer, Boolean

D. String, Integer, Boolean

Solution

1. Step 1: Identify each field's value type

   "name" is text, so String; "age" is a number, so Integer; "member" is true/false, so Boolean.

2. Step 2: Match with options

   String, Integer, Boolean matches String, Integer, Boolean in order. Others mismatch types.

3. Final Answer:

   String, Integer, Boolean -> Option D

4. Quick Check:

   Text, number, true/false = String, Integer, Boolean [OK]

Hint: Match field values to String, Integer, Boolean types [OK]

Common Mistakes:

• Confusing Integer with String for numbers
• Mixing Boolean and Integer types
• Assuming ObjectId for name field

4. You try to insert this document into MongoDB:
{ "date": "2023-01-01" }
But you want the date field to be stored as a BSON Date type. What is the issue and how to fix it?

medium

A. The date is a string; convert it to BSON Date using ISODate()

B. The date is missing; add a date field

C. The date format is invalid; use YYYY/DD/MM instead

D. MongoDB does not support Date type; use String instead

Solution

1. Step 1: Identify the current data type of date field

   The date is stored as a string because it is enclosed in quotes.

2. Step 2: Convert string to BSON Date type

   Use MongoDB's ISODate() function to store the date as BSON Date type.

3. Final Answer:

   The date is a string; convert it to BSON Date using ISODate() -> Option A

4. Quick Check:

   Date string needs ISODate() for BSON Date [OK]

Hint: Use ISODate() to store dates, not strings [OK]

Common Mistakes:

• Assuming string is automatically Date
• Changing date format incorrectly
• Believing MongoDB lacks Date type

5. You want to store a list of tags for a blog post in MongoDB. Which BSON data type should you use to store multiple tag strings together?

hard

A. Array

B. ObjectId

C. Boolean

D. Date

Solution

1. Step 1: Understand the need to store multiple values

   A list of tags means multiple values grouped together.

2. Step 2: Identify BSON type for multiple values

   Array is the BSON type used to store lists or collections of values.

3. Final Answer:

   Array -> Option A

4. Quick Check:

   Multiple values = Array type [OK]

Hint: Use Array type for lists of values [OK]

Common Mistakes:

• Using ObjectId for lists
• Choosing Boolean for multiple tags
• Trying to store list as Date