Change stream events (insert, update, delete) in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to watch for insert events in a MongoDB collection.

MongoDB

const changeStream = collection.watch([{ $match: { operationType: [1] } }]);

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

A"insert"

B"delete"

C"update"

D"replace"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'update' instead of 'insert' will watch for update events, not inserts.

Forgetting quotes around the operationType value causes syntax errors.

The operationType filter should be set to "insert" to watch for insert events.

2fill in blank

medium

Complete the code to listen for delete events from the change stream.

MongoDB

changeStream.on('change', (change) => { if (change.operationType === [1]) { console.log('Document deleted'); } });

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

A"insert"

B"update"

C"replace"

D"delete"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'update' or 'insert' will not detect delete events.

Missing quotes around the string causes errors.

To detect delete events, check if operationType equals "delete".

3fill in blank

hard

Fix the error in the code to correctly filter for update events in the change stream pipeline.

MongoDB

const pipeline = [{ $match: { operationType: [1] } }];

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

A"update"

Bupdate

Cupdates

D"updates"

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted update causes syntax errors.

Using plural 'updates' is incorrect; the correct value is 'update'.

The operationType value must be a string with quotes, so use "update".

4fill in blank

hard

Fill both blanks to create a change stream that listens for insert and delete events.

MongoDB

const pipeline = [{ $match: { operationType: { $in: [[1], [2]] } } }];

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

A"insert"

B"update"

C"delete"

D"replace"

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted strings causes errors.

Including wrong operation types like 'update' or 'replace' changes the filter.

The $in operator filters for multiple operation types. Use "insert" and "delete" to watch for those events.

5fill in blank

hard

Fill all three blanks to log the document key, operation type, and full document on insert events.

MongoDB

changeStream.on('change', (change) => { if (change.operationType === [1]) { console.log('Key:', change.[2]); console.log('Full Document:', change.[3]); } });

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

A"insert"

BdocumentKey

CfullDocument

Dns

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'update' or 'delete' instead of 'insert' changes the event type.

Accessing 'ns' instead of 'documentKey' or 'fullDocument' gives namespace info, not document data.

For insert events, operationType is "insert". The document key is in documentKey, and the full inserted document is in fullDocument.