Insert Data in Collections

Create Collection

To insert data in MongoDB Database, first we have to create a collection ( like table) and document data in it. To do this, lets start MongoDB client in terminal.

A collection is like a table in MongoDB. In a MongoDB database, we can create n numbers of collections. Inside collections, we have documents ( rows ) to store data in key-value pair.

Start Mongo Shell

In order to connect to MongoDB database, we have to start MongoDB shell first.

Start MongoDB client

Show all databases

Select a Database

Check Database Name

insertOne

insertOne method is used to insert single document in collection. insertOne was introduced in MongoDB 3.2.

{
    "_id": ObjectId("5eb44282ea2adece905a24b0"),
    "name": "swift",
    "type": "hatchback"
}
   

This is the final output in MongoDB Compass.

Primary Key

The ObjectId stored in "_id" is the primary key. The primary key is always unique for all documents.

It is always recommended to use natural primary keys in MongoDB. The primary key generated by MongoDB use 12 bytes of storage. Which means it can store 24 digits, 2 digits per byte. Lets try to understand primary keys pattern.

First four bytes are timestamp in seconds since EPOCH ( 1-jan-1947 00:00). Next three bytes are for machine. Next two for processid and last three bytes are increment.

insertMany

insertMany method introduced in 3.2 is used to insert multiple documents in collections. The argument in insertMany is an array of objects. See example

{
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("5eb5378791fc73f290f38251"),
                ObjectId("5eb5378791fc73f290f38252")
        ]
}
   

insert

The insert method is used to insert single or multiple documents in a collections . The is the most preferred method to insert data in mongoDB. The argument in insert method can be object ( single document ) or an array ( multiple documents ).

Insert Single

    WriteResult({ "nInserted" : 1 })
   

Insert Multiple

    BulkWriteResult({
        "writeErrors" : [ ],
        "writeConcernErrors" : [ ],
        "nInserted" : 2,
        "nUpserted" : 0,
        "nMatched" : 0,
        "nModified" : 0,
        "nRemoved" : 0,
        "upserted" : [ ]
})