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MongoDB insertOne() Method – db.Collection.insertOne()

Last Updated : 28 Jan, 2021
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In MongoDB, insertOne() method inserts a document into the collection. This method inserts only one document at a time. 

  • Using this method you can also create a collection by inserting documents.
  • You can insert documents with or without _id field. If you insert a document in the collection without _id field, then MongoDB will automatically add an _id field and assign it with a unique ObjectId. And if you insert a document with _id field, then the value of the _id field must be unique to avoid the duplicate key error.
  • This method can also throw either writeError or writeConcernError exception.
  • This method can also be used inside multi-document transactions.





    writeConcern: <document>



  • The first parameter is the document. Documents are a structure created of file and value pairs, similar to JSON objects.
  • The second parameter is optional.

Optional Parameter:

writeConcern: It is only used when you do not want to use the default write concern. The type of this parameter is a document.


This method returns :

  • Boolean acknowledged as true if write concern was enabled or false if write concern was disabled.
  • The insertedId field with the _id value of the inserted document.


In the following examples, we are working with:

Database: gfg

Collection: student

Document: No document but, we want to insert in the form of the student name and student marks.

  • Insert a single document without specifying the _id field

 Here, we are inserting the document whose name is Akshay and marks is 500 in the student collection.

db.student.insertOne({Name: "Akshay", Marks: 500})

  • Insert a single document with _id field

Here, we are inserting a document whose unique id is Stu102, name is Vishal, and marks is 230 in the student collection

db.student.insertOne({_id: "Stu102", Name: "Vishal", Marks: 230})

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