How to Use insertMany in MongoDB: Syntax and Examples

Use insertMany() in MongoDB to add multiple documents to a collection at once by passing an array of objects. It returns a result object with details about the inserted documents.

Syntax

The insertMany() method takes an array of documents to insert and an optional options object.

• documents: An array of objects representing the documents to insert.
• options (optional): Settings like ordered to control if insertion stops on error.

It returns a promise that resolves with an object containing the inserted IDs.

javascript

db.collection.insertMany(documents, options)

Example

This example shows how to insert three user documents into a users collection using insertMany(). It logs the inserted IDs on success.

javascript

const { MongoClient } = require('mongodb');

async function run() {
  const client = new MongoClient('mongodb://localhost:27017');
  try {
    await client.connect();
    const db = client.db('testdb');
    const users = db.collection('users');

    const result = await users.insertMany([
      { name: 'Alice', age: 25 },
      { name: 'Bob', age: 30 },
      { name: 'Charlie', age: 35 }
    ]);

    console.log('Inserted IDs:', result.insertedIds);
  } finally {
    await client.close();
  }
}

run().catch(console.dir);

Output

Inserted IDs: { '0': ObjectId('...'), '1': ObjectId('...'), '2': ObjectId('...') }

Common Pitfalls

Common mistakes when using insertMany() include:

• Passing a single object instead of an array, which causes an error.
• Not handling errors when ordered is true, causing the operation to stop on first failure.
• Ignoring the returned insertedIds which helps track inserted documents.

Always pass an array and consider using { ordered: false } to continue inserting even if some documents fail.

javascript

/* Wrong: Passing single object */
db.collection.insertMany({ name: 'Alice' }); // Error

/* Right: Passing array */
db.collection.insertMany([{ name: 'Alice' }]);

/* Using ordered option */
db.collection.insertMany(
  [{ _id: 1 }, { _id: 1 }],
  { ordered: false }
); // Continues inserting despite duplicate key error on second document

Quick Reference

Here is a quick summary of insertMany() usage:

Parameter	Description	Example
documents	Array of documents to insert	[{ name: 'A' }, { name: 'B' }]
options	Optional settings like ordered	{ ordered: false }
returns	Promise with insertedIds	{ insertedIds: { '0': ObjectId, '1': ObjectId } }

Key Takeaways

Use insertMany() to insert multiple documents by passing an array.

Always pass an array, not a single object, to insertMany().

Use the ordered option to control error handling during insertion.

Check the insertedIds in the result to confirm inserted documents.

Handle errors properly to avoid partial insert failures.