Update operators modify specific fields in a document without replacing the entire document. Always use them inside updateOne() or updateMany() to avoid accidentally overwriting your data.
// $set - set field value (creates field if it doesn't exist)
db.users.updateOne(
{ email: "alice@example.com" },
{ $set: { age: 30, city: "Boston", "address.zip": "02101" } }
)
// $unset - remove a field from the document
db.users.updateOne(
{ email: "alice@example.com" },
{ $unset: { temporaryToken: "" } }
)
// $inc - increment (or decrement with negative value)
db.users.updateOne({ _id: ObjectId("...") }, { $inc: { loginCount: 1 } })
db.products.updateOne({ sku: "LAPTOP-001" }, { $inc: { stock: -1 } })
// $mul - multiply a field value
db.products.updateOne({ sku: "LAPTOP-001" }, { $mul: { price: 1.1 } }) // 10% price increase
// $rename - rename a field
db.users.updateMany({}, { $rename: { "fname": "firstName", "lname": "lastName" } })
// $min - update only if new value is less than current
db.scores.updateOne({ userId: "u1" }, { $min: { lowestScore: 45 } })
// $max - update only if new value is greater than current
db.scores.updateOne({ userId: "u1" }, { $max: { highScore: 98 } })
// $currentDate - set field to current date
db.users.updateOne(
{ email: "alice@example.com" },
{ $currentDate: { lastLogin: true, lastModified: { $type: "timestamp" } } }
)// $push - append a value to an array
db.users.updateOne(
{ email: "alice@example.com" },
{ $push: { hobbies: "gaming" } }
)
// $push with $each - append multiple values
db.users.updateOne(
{ email: "alice@example.com" },
{ $push: { hobbies: { $each: ["cooking", "hiking"] } } }
)
// $push with $each, $slice, $sort - keep only last 5 sorted items
db.users.updateOne(
{ email: "alice@example.com" },
{
$push: {
recentViews: {
$each: [{ productId: "p1", viewedAt: new Date() }],
$slice: -5,
$sort: { viewedAt: -1 }
}
}
}
)
// $pop - remove first (-1) or last (1) element
db.users.updateOne({ email: "alice@example.com" }, { $pop: { hobbies: 1 } }) // remove last
db.users.updateOne({ email: "alice@example.com" }, { $pop: { hobbies: -1 } }) // remove first
// $pull - remove all elements matching a condition
db.users.updateOne(
{ email: "alice@example.com" },
{ $pull: { hobbies: "gaming" } }
)
db.orders.updateOne(
{ _id: ObjectId("...") },
{ $pull: { items: { qty: { $lt: 1 } } } }
)
// $addToSet - add only if value doesn't already exist (no duplicates)
db.users.updateOne(
{ email: "alice@example.com" },
{ $addToSet: { tags: "verified" } }
)// upsert: true - insert if no document matches the filter
db.pageViews.updateOne(
{ page: "/home" },
{ $inc: { views: 1 }, $setOnInsert: { createdAt: new Date() } },
{ upsert: true }
)
// arrayFilters - update specific elements in nested arrays
// Update the qty of a specific item in an order's items array
db.orders.updateOne(
{ _id: ObjectId("...") },
{ $set: { "items.$[item].qty": 5 } },
{ arrayFilters: [{ "item.productId": "LAPTOP-001" }] }
)
// Update all array elements matching a condition
db.students.updateMany(
{},
{ $set: { "grades.$[g].passed": true } },
{ arrayFilters: [{ "g.score": { $gte: 60 } }] }
)// Field operators:
// $set - set field value
// $unset - remove field
// $inc - increment/decrement
// $mul - multiply
// $rename - rename field
// $min - update if new value is smaller
// $max - update if new value is larger
// $currentDate - set to current date/timestamp
// $setOnInsert - set only on upsert insert
// Array operators:
// $push - append to array
// $pop - remove first/last element
// $pull - remove matching elements
// $pullAll - remove all listed values
// $addToSet - add if not already present
// $each - modifier for $push/$addToSet
// $slice - modifier to limit array size
// $sort - modifier to sort array elements
// $position - modifier to insert at position
// Positional operators:
// $ - first matching element
// $[] - all elements
// $[identifier] - filtered elements (with arrayFilters)Explore 500+ free tutorials across 20+ languages and frameworks.