db.collection.insert() (mongosh method)

Parameters

Write Concern

The insert() method uses the insert command, which uses the default write concern. To specify a different write concern, include the write concern in the options parameter.

Collection and _id Field Creation

If the collection does not exist, then insert() creates the collection.

If the document to insert does not specify an _id field, then mongod adds the _id field and assigns a unique ObjectId() for the document. Most drivers create an ObjectId and insert the _id field, but the mongod will create and populate the _id if the driver or application does not.

If the document contains an _id field, the _id value must be unique within the collection to avoid duplicate key error.

Transactions

insert() can be used inside distributed transactions.

Oplog Entries

If an insert() operation successfully inserts a document, the operation adds an entry on the oplog (operations log). If the operation fails, the operation does not add an entry on the oplog.

Insert a Document without Specifying an _id Field

The following example inserts a document without an _id field into the movies collection:

db.movies.insert( { title: "Inception", year: 2010, genres: [ "Action", "Sci-Fi" ] } )

{
  acknowledged: true,
  insertedIds: { '0': "..." }
}

Because the inserted document does not include _id, mongod creates and adds the _id field and assigns it a unique ObjectId() value.

The ObjectId values are specific to the machine and time when the operation is run. As such, your values may differ from those in the example.

Insert a Document Specifying an _id Field

The following example specifies the _id field in the document inserted into the movies collection. The value of _id must be unique within the collection to avoid a duplicate key error.

db.movies.insert( { _id: 10, title: "Inception", year: 2010 } )

{
  acknowledged: true,
  insertedIds: { '0': 10 }
}

Insert Multiple Documents

The following example performs a bulk insert by passing an array of documents to insert(). By default, MongoDB performs an ordered insert. With ordered inserts, if an error occurs during an insert of one of the documents, MongoDB returns on error without processing the remaining documents in the array.

The first document specifies an _id field. Because the second and third documents do not contain an _id field, mongod creates and adds the _id field for those documents during the insert:

db.movies.insert(
   [
     { _id: 11, title: "Inception", year: 2010, genres: [ "Action", "Sci-Fi" ] },
     { title: "The Matrix", year: 1999 },
     { title: "Interstellar", year: 2014 }
   ]
)

{
  acknowledged: true,
  insertedIds: {
    '0': 11,
    '1': "...",
    '2': "..."
  }
}

Perform an Unordered Insert

The following example performs an unordered insert of three documents. With unordered inserts, if an error occurs during an insert of one of the documents, MongoDB continues to insert the remaining documents in the array.

db.movies.insert(
   [
     { _id: 20, title: "2001: A Space Odyssey", year: 1968 },
     { _id: 21, title: "A Clockwork Orange", year: 1971 },
     { _id: 22, title: "The Shining", year: 1980 }
   ],
   { ordered: false }
)

Override Default Write Concern

The following operation to a replica set specifies a write concern of w: 2 with a wtimeout of 5000 milliseconds. This operation either returns after the write propagates to both the primary and one secondary, or times out after 5 seconds.

db.movies.insert(
    { title: "The Revenant", year: 2015 },
    { writeConcern: { w: 2, j: true, wtimeout: 5000 } }
)

Successful Results

Upon success, the returned WriteResult object contains information on the number of documents inserted:

WriteResult({ "nInserted" : 1 })

Write Concern Errors

If insert() encounters write concern errors, the results include the WriteResult.writeConcernError field:

WriteResult({
  "nInserted" : 1,
  "writeConcernError"({
     "code" : 64,
     "errmsg" : "waiting for replication timed out",
     "errInfo" : {
       "wtimeout" : true,
       "writeConcern" : {
         "w" : "majority",
         "wtimeout" : 100,
         "provenance" : "getLastErrorDefaults"
       }
     }
})

Errors Unrelated to Write Concern

If insert() encounters a non-write concern error, the results include the WriteResult.writeError field:

WriteResult({
   "nInserted" : 0,
   "writeError" : {
      "code" : 11000,
      "errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: test.foo.$_id_  dup key: { : 1.0 }"
   }
})