insertOne method in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert a single document into the collection.

MongoDB

db.collection.[1]({ name: "Alice", age: 25 })

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

AinsertOne

BinsertMany

CfindOne

DupdateOne

Attempts:

3 left

💡 Hint

Common Mistakes

Using insertMany instead of insertOne for a single document.

Using findOne which only reads data.

Using updateOne which modifies existing data.

The insertOne method inserts a single document into the collection.

2fill in blank

medium

Complete the code to insert a document and handle the returned promise.

MongoDB

db.collection.insertOne({ item: "book", qty: 10 }).[1](result => console.log(result.insertedId))

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

Acatch

Bthen

Cawait

Dfinally

Attempts:

3 left

💡 Hint

Common Mistakes

Using catch instead of then for success handling.

Using await without async function.

Using finally which runs regardless of success or failure.

The then method handles the promise when the insertion succeeds.

3fill in blank

hard

Fix the error in the code to correctly insert a document.

MongoDB

db.collection.insertOne({ name: "Bob", age: 30 [1] )

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

A}

B]

C)

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Closing the object with a square bracket instead of curly brace.

Missing the closing brace causes syntax errors.

Adding a semicolon inside the method call.

The document object must be closed with a curly brace } before the closing parenthesis.

4fill in blank

hard

Fill both blanks to insert a document and print the inserted ID.

MongoDB

db.collection.[1]({ name: "Eve", active: true }).[2](res => console.log(res.insertedId))

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

AinsertOne

BinsertMany

Cthen

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using insertMany for a single document.

Using catch instead of then for success handling.

Use insertOne to add one document and then to handle the success.

5fill in blank

hard

Fill all three blanks to insert a document, handle success, and catch errors.

MongoDB

db.collection.[1]({ username: "john_doe" }).[2](res => console.log(res.insertedId)).[3](err => console.error(err))

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

AinsertOne

Bthen

Ccatch

DinsertMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using insertMany instead of insertOne.

Mixing up then and catch methods.

Use insertOne to insert, then to handle success, and catch to handle errors.

Practice

1. What does the insertOne method do in MongoDB?

easy

A. Adds a single document to a collection

B. Deletes a document from a collection

C. Updates multiple documents in a collection

D. Finds documents matching a query

Solution

1. Step 1: Understand the purpose of insertOne

   The insertOne method is designed to add exactly one new document to a MongoDB collection.

2. Step 2: Compare with other operations

   Deleting, updating, or finding documents are different operations and use other methods like deleteOne, updateMany, or find.

3. Final Answer:

   Adds a single document to a collection -> Option A

4. Quick Check:

   insertOne = Adds one document [OK]

Hint: insertOne always adds exactly one document [OK]

Common Mistakes:

• Confusing insertOne with update or delete methods
• Thinking insertOne adds multiple documents
• Assuming insertOne returns the document itself

2. Which of the following is the correct syntax to insert a document with insertOne in MongoDB?

easy

A. db.collection.insertOne['name', 'Alice', 'age', 25]

B. db.collection.insertOne({name: 'Alice', age: 25})

C. db.collection.insertOne('name: Alice, age: 25')

D. db.collection.insertOne(name='Alice', age=25)

Solution

1. Step 1: Identify correct method call format

   The insertOne method requires a single document as an object inside parentheses.

2. Step 2: Check each option's syntax

   db.collection.insertOne({name: 'Alice', age: 25}) uses correct JavaScript object notation inside parentheses. Options B, C, and D use incorrect syntax for MongoDB commands.

3. Final Answer:

   db.collection.insertOne({name: 'Alice', age: 25}) -> Option B

4. Quick Check:

   insertOne uses object in parentheses [OK]

Hint: Use curly braces inside parentheses for insertOne [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Passing a string instead of an object
• Using assignment syntax inside insertOne

3. What will be the output of the following code?

const result = db.users.insertOne({username: 'john_doe', active: true});
printjson(result);

medium

A. An error because printjson is not defined

B. The inserted document itself

C. { acknowledged: true, insertedId: ObjectId('...') }

D. An empty object {}

Solution

1. Step 1: Understand insertOne return value

   The insertOne method returns an object with acknowledged true and the insertedId of the new document.

2. Step 2: Analyze printjson output

   Printing the result shows this object, not the document itself or an error.

3. Final Answer:

   { acknowledged: true, insertedId: ObjectId('...') } -> Option C

4. Quick Check:

   insertOne returns confirmation object [OK]

Hint: insertOne returns status and new document ID [OK]

Common Mistakes:

• Expecting the inserted document as output
• Thinking printjson causes an error
• Assuming insertOne returns empty object

4. Identify the error in this code snippet:

db.products.insertOne(name: 'Book', price: 15);

medium

A. Missing curly braces around the document

B. insertOne cannot insert documents with price field

C. Using semicolon instead of comma between fields

D. insertOne requires two arguments

Solution

1. Step 1: Check document syntax for insertOne

   The document to insert must be an object enclosed in curly braces {}.

2. Step 2: Identify the error in the code

   The code passes fields without curly braces, which is invalid syntax for insertOne.

3. Final Answer:

   Missing curly braces around the document -> Option A

4. Quick Check:

   insertOne needs object with braces [OK]

Hint: Always wrap inserted data in curly braces { } [OK]

Common Mistakes:

• Omitting curly braces for the document
• Using semicolons inside object literal
• Thinking insertOne needs multiple arguments

5. You want to insert a user document with fields name, email, and age. Which insertOne call correctly adds this document and returns the new document's ID?

hard

A. const res = db.users.insertOne('name: Eva, email: [e-mail], age: 30'); return res.insertedId;

B. const res = db.users.insertOne(['name', 'Eva', 'email', '[e-mail]', 'age', 30]); return res.insertedId;

C. const res = db.users.insertOne({name: 'Eva', email: '[e-mail]', age: 30}); return res;

D. const res = db.users.insertOne({name: 'Eva', email: '[e-mail]', age: 30}); return res.insertedId;

Solution

1. Step 1: Verify correct document format and method usage

   The document must be an object with keys and values inside curly braces. The insertOne method returns an object containing insertedId.

2. Step 2: Check return value for new document ID

   const res = db.users.insertOne({name: 'Eva', email: '[e-mail]', age: 30}); return res.insertedId; correctly returns res.insertedId, which is the new document's unique ID. const res = db.users.insertOne({name: 'Eva', email: '[e-mail]', age: 30}); return res; returns the whole result object, not just the ID. Options A and B use wrong argument types.

3. Final Answer:

   const res = db.users.insertOne({name: 'Eva', email: '[e-mail]', age: 30}); return res.insertedId; -> Option D

4. Quick Check:

   insertOne returns insertedId in result [OK]

Hint: insertOne returns insertedId inside result object [OK]

Common Mistakes:

• Passing array or string instead of object
• Returning whole result instead of insertedId
• Not wrapping fields in curly braces