Insert operation
The insert operation adds a new document to a collection.
Insert a single document
The insertOne() command is used to add a single document into a collection, using this syntax format:
db.collection.insertOne({field1: value1, field2: value2,.... fieldN: valueN})
The example below depicts how a single document can be added to a collection. If a collection does not exist, the insert command automatically creates one.
db.scientists.insertOne({
  name: {
    firstname: 'Thomas',
    lastname: 'Edison'
  },
  born: 1847,
  invention: 'lightbulb'
})
If the operation is successful, you will get a response with acknowledged set to true, and the autogenerated ObjectId of the document that looks like this:
{
  acknowledged: true,
  insertedId: ObjectId("6346fcafd7a4a1b0b38eb2db")
}
Insert multiple documents at once
A collection can contain multiple documents.
Using the insertMany() command, you can add multiple documents to a collection at once.
db.collection_name.insertMany([{ document1 }, { document2 }, ...{ documentN }])
The following example shows how to insert multiple documents into a collection:
db.scientists.insertMany([
  {
    name: {
      firstname: 'Alan',
      lastname: 'Turing'
    },
    born: 1912,
    invention: 'Turing Machine'
  },
  {
    name: {
      firstname: 'Graham',
      lastname: 'Bell'
    },
    born: 1847,
    invention: 'telephone'
  },
  {
    name: {
      firstname: 'Ada',
      lastname: 'Lovelace'
    },
    born: 1815,
    invention: 'computer programming'
  }
])
You can retrieve all the documents in the collection with this command: db.scientists.find({})