MEAN MongoDB Schema Design and CRUD Operations

Question 1

In MongoDB, which design pattern should you prefer when related data is always accessed together and the 'many' side has a bounded, small number of items?

Accepted Answer

Embedding the related documents inside the parent document

Answer

Embedding is preferred when data is always read together and the nested array won't grow unboundedly (e.g., a blog post's comments when there are fewer than a few hundred). It avoids extra queries and keeps related data in one atomic document.

Question 2

Which MongoDB update operator increments a numeric field by a specified amount without reading the document first?

Accepted Answer

$inc

Answer

$inc atomically increments (or decrements with a negative value) a numeric field by the specified amount. For example, { $inc: { views: 1 } } adds 1 to the views field. $set replaces a field's value entirely.

Question 3

What does `db.collection.findOneAndUpdate()` return by default?

Accepted Answer

The document as it appeared BEFORE the update was applied

Answer

By default, findOneAndUpdate() returns the original document before the update. To return the updated document, you must pass { returnDocument: 'after' } (or returnNewDocument: true in older drivers) as an option.

Question 4

Which MongoDB CRUD method should you use to insert multiple documents in a single network round-trip?

Accepted Answer

insertMany()

Answer

insertMany() accepts an array of documents and inserts them all in one operation, drastically reducing network overhead compared to calling insertOne() repeatedly. bulkWrite() also works but is more complex and designed for mixed operation types.

Question 5

In a Mongoose schema, what is the purpose of setting `{ timestamps: true }` as a schema option?

Accepted Answer

It automatically adds and manages `createdAt` and `updatedAt` fields on each document

Answer

When timestamps: true is set in a Mongoose schema, Mongoose automatically adds createdAt (set once on insert) and updatedAt (updated on every save/update) fields to every document, handling the bookkeeping automatically.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN MongoDB Schema Design and CRUD Operations