Why should you care?

Payments and healthcare cannot accept orders missing total or patientId. Validation catches bad writes before they poison analytics.

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.createCollection("orders", {
  validator: {
    $jsonSchema: {
      bsonType: "object",
      required: ["userId", "total", "status"],
      properties: {
        userId: { bsonType: "objectId" },
        total: { bsonType: ["double", "int", "decimal"], minimum: 0 },
        status: { enum: ["placed", "paid", "shipped", "cancelled"] }
      }
    }
  },
  validationLevel: "moderate",
  validationAction: "error"
})
db.orders.insertOne({ userId: ObjectId(), total: 499, status: "placed" })

Run Example »

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

What happened?

• createCollection attaches a $jsonSchema validator.
• required fields must exist.
• status must be one of the enum values.
• Invalid inserts error when validationAction is error.

Practice next

1. Create orders with the validator (drop first if it exists in practice DB).
2. Insert a valid order.
3. Try insert without total — expect failure.
4. Add required currency enum ["INR","USD"].
5. Try validationAction: "warn" on a scratch collection.

Remember

$jsonSchema validates documents on write. Use required + types for critical collections. moderate level validates only new/changed fields.

Order integrity for finance

Checkout service cannot insert status "shipped" without going through payment — enum limits garbage states.

Outcome: Downstream billing jobs see only known statuses.