MongoDB Insert Document

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In this post, we will learn how to insert single and multiple documents in MongoDB collection.

Insert a Single Document

db.collection.insertOne() inserts a single document into a collection.

The following example inserts a new document into the posts collection. If the document does not specify an _id field, MongoDB adds the _id field with an ObjectId value to the new document.

> db.posts.insertOne({ title: 'MongoDB Overview', description: 'MongoDB is no sql database', by: 'Java Guides', url: 'https://www.javaguides.net', tags: ['mongodb', 'database', 'NoSQL'], likes: 500 }); { "acknowledged" : true, "insertedId" : ObjectId("5e1823977695f4d696a05984") } 

insertOne() returns a document that includes the newly inserted document’s _id field value.

Here "posts" is our collection name. If the collection doesn't exist in the database, then MongoDB will create this collection and then insert a document into it.

To retrieve the document that you just inserted, query the collection:

> db.posts.find().pretty(); { "_id" : ObjectId("5e198ead41b7a7bd66f65982"), "title" : "MongoDB Overview", "description" : "MongoDB is no sql database", "by" : "Java Guides", "url" : "https://www.javaguides.net", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 500 }

The below diagram shows the summary of all the commands used to insert a single document:

Insert Multiple Documents

db.collection.insertMany() can insert multiple documents into a collection. Pass an array of documents to the method.

The following example inserts two new documents into the posts collection. If the documents do not specify an _id field, MongoDB adds the _id field with an ObjectId value to each document.

db.posts.insertMany([ { title: 'MongoDB Overview', description: 'MongoDB is no sql database', by: 'Java Guides', url: 'https://javaguides.net', tags: ['mongodb', 'database', 'NoSQL'], likes: 100 }, { title: 'NoSQL Database', description: "NoSQL database doesn't have tables", by: 'Java Guides', url: 'https://javaguides.net', tags: ['mongodb', 'database', 'NoSQL'], likes: 20, comments: [ { user:'user1', message: 'My first comment', dateCreated: new Date(2013,11,10,2,35), like: 0 } ] } ]); { "acknowledged" : true, "insertedIds" : [ ObjectId("5e18246f7695f4d696a05985"), ObjectId("5e18246f7695f4d696a05986") ] } 

insertMany() returns a document that includes the newly inserted documents _id field values. See the reference for an example.

To retrieve the inserted documents, query the collection:

> db.posts.find().pretty(); { "_id" : ObjectId("5e198ead41b7a7bd66f65982"), "title" : "MongoDB Overview", "description" : "MongoDB is no sql database", "by" : "Java Guides", "url" : "https://www.javaguides.net", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 500 } { "_id" : ObjectId("5e198f8e41b7a7bd66f65983"), "title" : "MongoDB Overview", "description" : "MongoDB is no sql database", "by" : "Java Guides", "url" : "https://javaguides.net", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 } { "_id" : ObjectId("5e198f8e41b7a7bd66f65984"), "title" : "NoSQL Database", "description" : "NoSQL database doesn't have tables", "by" : "Java Guides", "url" : "https://javaguides.net", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 20, "comments" : [ { "user" : "user1", "message" : "My first comment", "dateCreated" : ISODate("2013-12-10T09:35:00Z"), "like" : 0 } ] }

Insert Behavior

Collection Creation

If the collection does not currently exist, insert operations will create the collection.

_id Field

In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the MongoDB driver automatically generates an ObjectId for the _id field.

This also applies to documents inserted through update operations with upsert: true.

Atomicity

All write operations in MongoDB are atomic on the level of a single document.