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$divide

The $divide operator divides one number by another.

📌 Syntax

{ "$divide": [ <numerator>, <denominator> ] }

Both arguments must resolve to numeric values. Division by zero will result in an error or null.

✅ Base Example 1 – Simple Division

📥 Input Document

{ "total": 100, "parts": 4 }

📌 Expression

{ "$divide": ["$total", "$parts"] }

📤 Output

25

✅ Base Example 2 – Convert Cents to Dollars

📥 Input Document

{ "amountInCents": 1250 }

📌 Expression

{ "$divide": ["$amountInCents", 100] }

📤 Output

12.5

🧱 Ecommerce Example – Compute Unit Price per Item

📌 Pipeline

[
  { "$unwind": "$items" },
  {
    "$project": {
      "product": "$items.name",
      "unitPrice": {
        "$divide": ["$items.totalPrice", "$items.quantity"]
      }
    }
  }
]

📥 Input Document

{
  "orderId": 2002,
  "items": [
    { "name": "Chair", "totalPrice": 300, "quantity": 3 },
    { "name": "Desk", "totalPrice": 500, "quantity": 1 }
  ]
}

📤 Output

[
  { "product": "Chair", "unitPrice": 100 },
  { "product": "Desk", "unitPrice": 500 }
]

🧱 Ecommerce Example – Discount Percent

📌 Expression

{ "$divide": ["$discount", "$price"] }

Used to compute the proportion of discount relative to the price.

📥 Input Document

{ "price": 250, "discount": 25 }

📤 Output

0.1

🔧 Common Use Cases

  • Price per unit
  • Percentage calculations
  • Normalization
  • $add, $subtract, $multiply, $mod
  • $cond, $round, $project

🧠 Notes

  • If denominator is 0, the result may be null or cause an error.
  • Always validate for zero if dynamic input is used.