MongoDB $nor Operator

What You’ll Learn

The $nor operator performs a logical NOR on an array of query conditions. A document matches only when none of the conditions are true — the opposite of $or.

Definition and Usage

In MongoDB, the $nor operator selects documents where no sub-expression in its array matches. Think of it as: “exclude documents that satisfy condition A or condition B.” Formally, $nor is equivalent to NOT (A OR B OR ...).

This is especially useful when exclusion rules span different fields. For example, keep products that are neither out of stock nor priced below $10.

📝 Syntax

The $nor operator takes an array of query expressions:

{ $nor: [ <condition1>, <condition2>, ... ] }

Example (in find or $match)

{
  $nor: [
    { inStock: false },
    { price: { $lt: 10 } }
  ]
}

Syntax Rules

• Array required — wrap each condition as a separate object in the array.
• Query operator — use in find() and $match (not in $project directly).
• Each array element is a complete query expression (field + operator).
• A document matches when zero sub-expressions match.
• If any one condition matches, the document is excluded.
• For excluding multiple values on one field, $nin is often simpler.

Examples Gallery

Exclude products that are out of stock or too cheap, filter eligible users, and apply $nor in aggregation pipelines.

[
  { "_id": ObjectId("609c26812e9274a86871bc6a"), "name": "Widget",  "inStock": true,  "price": 25 },
  { "_id": ObjectId("609c26812e9274a86871bc6b"), "name": "Cheap",   "inStock": true,  "price": 5 },
  { "_id": ObjectId("609c26812e9274a86871bc6c"), "name": "Old",     "inStock": false, "price": 50 },
  { "_id": ObjectId("609c26812e9274a86871bc6d"), "name": "Clearance","inStock": false, "price": 3 }
]

db.products.find({
  $nor: [
    { inStock: false },
    { price: { $lt: 10 } }
  ]
})

{ "name": "Widget", "inStock": true, "price": 25 }

db.users.find({
  $nor: [
    { status: "inactive" },
    { age: { $lt: 18 } }
  ]
})

// Alice: active, age 25  → included
// Bob:   inactive, age 30 → excluded (inactive)
// Carol: active, age 16  → excluded (under 18)

db.orders.aggregate([
  {
    $match: {
      $nor: [
        { status: "cancelled" },
        { status: "refunded" },
        { total: { $lte: 0 } }
      ]
    }
  },
  {
    $group: {
      _id: "$customerId",
      orderCount: { $sum: 1 },
      revenue: { $sum: "$total" }
    }
  }
])

// These are equivalent for one field:
db.orders.find({
  status: { $nin: [ "cancelled", "refunded" ] }
})

db.orders.find({
  $nor: [
    { status: "cancelled" },
    { status: "refunded" }
  ]
})

db.products.find({
  $expr: {
    $not: {
      $or: [
        { $eq: [ "$inStock", false ] },
        { $lt: [ "$price", 10 ] }
      ]
    }
  }
})

// Equivalent to the $nor example above

🚀 Use Cases

• Catalog filtering — exclude products that are out of stock or below a minimum price.
• User eligibility — block users who are inactive or below a minimum age.
• Order cleanup — remove cancelled, refunded, or invalid orders before reporting.
• Complex exclusions — combine unrelated field conditions in one filter.

💡 Best Practices