Why should you care?

One order document can embed line items. That matches how a checkout API already thinks — one payload, one stored record.

See it live — copy this example

Open mongosh or MongoDB Compass, select database nosqlverse, then run the example. Change one field and run again.

db.orders.insertOne({
  _id: ObjectId("64f000000000000000000001"),
  userId: ObjectId("64f0000000000000000000aa"),
  items: [
    { sku: "KB-01", qty: 1, price: 4499 },
    { sku: "MS-02", qty: 2, price: 999 }
  ],
  status: "placed",
  placedAt: new Date()
})
db.orders.findOne({ status: "placed" })

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• The order has a fixed _id, a reference-style userId, an items array of subdocuments, a status string, and a Date.
• findOne returns the first matching order.
• Nested items live inside the same document.

Practice next

1. Insert the order document (or let MongoDB auto-create _id).
2. Run findOne and expand items in Compass.
3. Add a field couponCode with updateOne (next lessons).
4. Embed shipping: { city: "Bengaluru", pincode: "560001" }.
5. Insert without _id and inspect the auto ObjectId.

Remember

Documents are the unit of data in MongoDB. _id uniquely identifies each document in a collection. Nest related data when it is read together.

Swiggy-style order snapshot

When you place food, the order document stores restaurant name and item prices at order time even if the menu changes later.

Outcome: Historical orders stay accurate for support and invoices.