MongoDB Insert Document

This post will help us to learn How to add document in the MongoDB collection.

MongoDB has `insert()` and `save()` method to add a document into collection.

Syntax:

db.COLLECTION_NAME.insert(document)

Insert Single record:

Example:

> use learnmongodb
switched to db learnmongodb
> db.books.insert({
    'title':'MongoDB',
    'description':'Learn MongoDB with NoSQL',
    'version':'4.x'
    })
WriteResult({ "nInserted" : 1 })

[OR]

> db.books.insertOne({
    'title':'MongoDB',
    'description':'Learn MongoDB with NoSQL',
    'version':'4.x'
    })
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5b8e859670e393ef22ee63ed")
}
>

insertOne() - Return Value: It returns the _id of the document inserted into the database.

insert() or insertOne() method will create a new collection If It does not exist in selected MongoDB.

To retrieve the inserted documents from the collection, We need to use find() method.

> db.books.find()
{ "_id" : ObjectId("5b8e859670e393ef22ee63ed"), "title" : "MongoDB", "description" : "Learn MongoDB with NoSQL", "version" : "4.x" }
> db.books.find().pretty()
{
        "_id" : ObjectId("5b8e859670e393ef22ee63ed"),
        "title" : "MongoDB",
        "description" : "Learn MongoDB with NoSQL",
        "version" : "4.x"
}
>

In above sample, We have learned to insert a document and displayed data from collection using find() method.

Insert Multiple records:

To insert multiple documents in a single query, We have to pass an array of documents.

Example:

> db.books.insert([
    {
    'title':'PHP',
    'description':'Learn PHP with MongoDB',
    'version':'4.x'
    },
    {
    'title':'JAVA',
    'description':'Learn JAVA with MongoDB',
    'version':'4.x'
    },
    {
    'title':'C#',
    'description':'Learn C# with MongoDB',
    'version':'4.x'
    },
    ])
BulkWriteResult({
        "writeErrors" : [ ],
        "writeConcernErrors" : [ ],
        "nInserted" : 3,
        "nUpserted" : 0,
        "nMatched" : 0,
        "nModified" : 0,
        "nRemoved" : 0,
        "upserted" : [ ]
})
>

[OR]

> db.books.insertMany([
    {
    'title':'PHP',
    'description':'Learn PHP with MongoDB',
    'version':'4.x'
    },
    {
    'title':'JAVA',
    'description':'Learn JAVA with MongoDB',
    'version':'4.x'
    },
    {
    'title':'C#',
    'description':'Learn C# with MongoDB',
    'version':'4.x'
    },
    ])
{
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("5b8e877270e393ef22ee63ee"),
                ObjectId("5b8e877270e393ef22ee63ef"),
                ObjectId("5b8e877270e393ef22ee63f0")
        ]
}
>

insertMany() - Return Value: It returns the _ids of the documents inserted into the database.

To retrieve the inserted records,

> db.books.find().pretty()
{
        "_id" : ObjectId("5b8e859670e393ef22ee63ed"),
        "title" : "MongoDB",
        "description" : "Learn MongoDB with NoSQL",
        "version" : "4.x"
}
{
        "_id" : ObjectId("5b8e877270e393ef22ee63ee"),
        "title" : "PHP",
        "description" : "Learn PHP with MongoDB",
        "version" : "4.x"
}
{
        "_id" : ObjectId("5b8e877270e393ef22ee63ef"),
        "title" : "JAVA",
        "description" : "Learn JAVA with MongoDB",
        "version" : "4.x"
}
{
        "_id" : ObjectId("5b8e877270e393ef22ee63f0"),
        "title" : "C#",
        "description" : "Learn C# with MongoDB",
        "version" : "4.x"
}
>

_id Field:

If a document doesn't have a `_id` field, MongoDB will add new field `_id` in the document and assign a new unique object id to that field before inserting that record in the database.

If a document is having `_id`, It must be unique. Otherwise, we will get a duplicate key error.

Insert Document with `_id`:

> db.books.insert({
            "_id" : 123456789,
            "title" : "NodeJS",
            "description" : "Learn JAVA with MongoDB",
            "version" : "4.x"
    })
WriteResult({ "nInserted" : 1 })
> db.books.find().pretty()
{
        "_id" : 123456789,
        "title" : "NodeJS",
        "description" : "Learn JAVA with MongoDB",
        "version" : "4.x"
}
>

Add Document using Save() method:

To insert a document, We can use save() method instead of insert() method.

- If you do not specify `_id` in the document, It will add a new document like insert() method.

- If you specify `_id` in the document, It will replace that document data.