MongoDB Insert

Learn how to add documents to MongoDB collections

➕ Inserting Documents

Inserting documents in MongoDB means adding new data records to collections. You can insert single documents with insertOne() or multiple documents at once using insertMany() method for efficient data storage. 


// Insert a single document
db.users.insertOne({ name: "Alice", age: 25 })

// Insert multiple documents
db.users.insertMany([
    { name: "Bob", age: 30 },
    { name: "Carol", age: 28 }
])

Insert Methods

MongoDB provides several methods to insert documents into collections. Each method serves different purposes depending on whether you're adding one or multiple documents at a time.

1️⃣

insertOne()

Insert a single document 

db.users.insertOne({...})
📚

insertMany()

Insert multiple documents 

db.users.insertMany([...])
🆔

Auto _id

MongoDB adds unique _id automatically 

_id: ObjectId("...")
✅

Return Value

Get inserted document IDs 

insertedId: "..."

🔹 Insert One Document

Use insertOne() to add a single document to a collection: 

// Insert one user
db.users.insertOne({
    name: "John Smith",
    email: "[email protected]",
    age: 32,
    city: "New York"
})

// MongoDB returns the inserted ID
// { acknowledged: true, insertedId: ObjectId("...") }

Output:

✓ Document inserted successfully

insertedId: ObjectId("507f1f77bcf86cd799439011")

🔹 Insert Multiple Documents

Use insertMany() to add multiple documents in a single operation: 

// Insert multiple products
db.products.insertMany([
    {
        name: "Laptop",
        price: 999,
        category: "Electronics"
    },
    {
        name: "Mouse",
        price: 25,
        category: "Accessories"
    },
    {
        name: "Keyboard",
        price: 75,
        category: "Accessories"
    }
])

// Returns array of inserted IDs

Output:

✓ 3 documents inserted

insertedIds: [ ObjectId("..."), ObjectId("..."), ObjectId("...") ]

🔹 Automatic _id Field

MongoDB automatically adds a unique _id field to each document if you don't provide one: 

// Without _id (MongoDB creates it)
db.books.insertOne({
    title: "MongoDB Guide",
    author: "Jane Doe"
})

// With custom _id
db.books.insertOne({
    _id: "book001",
    title: "Advanced MongoDB",
    author: "John Smith"
})

Output:

Document 1: _id: ObjectId("507f191e810c19729de860ea")

Document 2: _id: "book001"

🔹 Insert with Nested Documents

You can insert documents with nested objects and arrays: 

// Insert document with nested data
db.customers.insertOne({
    name: "Sarah Johnson",
    email: "[email protected]",
    address: {
        street: "123 Main St",
        city: "Boston",
        state: "MA",
        zip: "02101"
    },
    orders: [
        { item: "Laptop", price: 999 },
        { item: "Mouse", price: 25 }
    ],
    registered: new Date()
})

Output:

✓ Document with nested data inserted

🔹 Insert Options

You can pass options to control insert behavior: 

// Insert with ordered option (default: true)
db.items.insertMany(
    [
        { name: "Item 1" },
        { name: "Item 2" },
        { name: "Item 3" }
    ],
    { ordered: false }  // Continue on error
)

// Insert with write concern
db.logs.insertOne(
    { message: "System started" },
    { writeConcern: { w: "majority" } }
)

Options Explained:

  • ordered: If false, continues inserting even if one fails
  • writeConcern: Controls acknowledgment of write operations

🔹 Handling Insert Errors

MongoDB returns errors if insertion fails: 

// Duplicate _id error
db.users.insertOne({ _id: 1, name: "Alice" })
db.users.insertOne({ _id: 1, name: "Bob" })  // Error!

// Catch errors in application code
try {
    db.users.insertOne({ _id: 1, name: "Charlie" })
} catch (error) {
    print("Insert failed: " + error)
}

Output:

✗ Error: E11000 duplicate key error

🔹 Complete Example

Here's a practical example of inserting various types of data: 

// Switch to database
use schoolDB

// Insert single student
db.students.insertOne({
    studentId: "S001",
    name: "Emma Wilson",
    age: 20,
    major: "Computer Science",
    gpa: 3.8
})

// Insert multiple courses
db.courses.insertMany([
    {
        courseId: "CS101",
        title: "Intro to Programming",
        credits: 3,
        instructor: "Dr. Smith"
    },
    {
        courseId: "CS201",
        title: "Data Structures",
        credits: 4,
        instructor: "Dr. Johnson"
    }
])

// Insert enrollment with references
db.enrollments.insertOne({
    studentId: "S001",
    courseId: "CS101",
    semester: "Fall 2024",
    grade: null  // Not yet graded
})

// Verify insertions
db.students.countDocuments()
db.courses.countDocuments()
db.enrollments.countDocuments()

Output:

✓ Students: 1

✓ Courses: 2

✓ Enrollments: 1

🧠 Test Your Knowledge

Which method would you use to insert multiple documents at once?