MongoDB Insert

Inserting a Single Document

db.collection.insertOne(document) writes exactly one document to a collection, creating the collection first if it doesn't already exist. It returns a result object containing acknowledged: true and an insertedId, which is either the _id you supplied or the ObjectId MongoDB generated for you.

Inserting Many Documents at Once

db.collection.insertMany(documentsArray) writes an array of documents in a single call, which is far more efficient than looping over insertOne(). By default the inserts are ordered, meaning MongoDB stops at the first error; passing { ordered: false } tells it to attempt every document and report all failures together.

Handling Duplicate Keys and Errors

• Every document's _id must be unique within its collection
• Inserting a duplicate _id raises a duplicate key error (E11000)
• Ordered inserts (the default) stop at the first failed document
• Unordered inserts ({ ordered: false }) skip failures and keep going
• Each document is written atomically, but a multi-document insertMany() as a whole is not

db.products.insertOne({
  name: "Wireless Mouse",
  price: 24.99,
  inStock: true
})

db.products.insertMany([
  { name: "Keyboard", price: 49.99 },
  { name: "Monitor Stand", price: 19.5 },
  { name: "USB Hub", price: 15.0 }
])

db.products.insertMany(
  [
    { _id: 1, name: "Webcam" },
    { _id: 1, name: "Duplicate ID" },
    { _id: 2, name: "Headset" }
  ],
  { ordered: false }
)