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Insert Documents

On this page

  • Insert Documents in the MongoDB Atlas UI
  • Insert a Single Document
  • Insert Multiple Documents
  • Insert Behavior

Use the Select your language drop-down menu in the upper-right to set the language of the following examples or select MongoDB Compass.


This page provides examples of insert operations in MongoDB.

You can insert documents in MongoDB by using the following methods:

  • Your programming language's driver.

  • The MongoDB Atlas UI. To learn more, see Insert Documents in the MongoDB Atlas UI.

  • MongoDB Compass.

Note

Creating a Collection

If the collection does not currently exist, insert operations will create the collection.

To insert a document in the MongoDB Atlas UI, complete the following steps. To learn more about working with documents in the MongoDB Atlas UI, see Create, View, Update, and Delete Documents.

1
  1. In the MongoDB Atlas UI, click Database in the sidebar.

  2. For the database deployment to which you want to add documents, click Browse Collections.

  3. In the left navigation pane, select the database.

  4. In the left navigation pane, select the collection.

2
  1. Click Insert Document.

  2. Click the {} icon, which opens the JSON view.

  3. Paste the document array into the text entry field. For example, the following entry creates four documents, each of which contain three fields:

    [
    { "prodId": 100, "price": 20, "quantity": 125 },
    { "prodId": 101, "price": 10, "quantity": 234 },
    { "prodId": 102, "price": 15, "quantity": 432 },
    { "prodId": 103, "price": 17, "quantity": 320 }
    ]
3

MongoDB Atlas adds the documents to the collection.

db.collection.insertOne() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, MongoDB adds the _id field with an ObjectId value to the new document. See Insert Behavior.

To insert a single document using MongoDB Compass:

  1. Navigate to the collection you wish to insert the document into:

    1. In the left-hand MongoDB Compass navigation pane, click the database to which your target collection belongs.

    2. From the database view, click the target collection name.

  2. Click the Insert Document button:

    Compass insert button
  3. For each field in the document, select the field type and fill in the field name and value. Add fields by clicking the last line number, then clicking Add Field After ...

    • For Object types, add nested fields by clicking the last field's number and selecting Add Field After ...

    • For Array types, add additional elements to the array by clicking the last element's line number and selecting Add Array Element After ...

  4. Once all fields have been filled out, click Insert.

The following example inserts a new document into the test.inventory collection:

IMongoCollection.InsertOne() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the C# driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

Collection.InsertOne inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

com.mongodb.reactivestreams.client.MongoCollection.insertOne inserts a single document into a collection with the Java Reactive Streams Driver:

{ item: "canvas", qty: 100, tags: ["cotton"], size: { h: 28, w: 35.5, uom: "cm" } }

The following example inserts the document above into the inventory collection. If the document does not specify an _id field, the driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

com.mongodb.client.MongoCollection.insertOne inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

motor.motor_asyncio.AsyncIOMotorCollection.insert_one inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the Motor driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

Collection.insertOne() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the Node.js driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

MongoDB::Collection::insert_one() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the Perl driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

MongoDB\\Collection::insertOne() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the PHP driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

pymongo.collection.Collection.insert_one inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the PyMongo driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

Mongo::Collection#insert_one() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the Ruby driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

collection.insertOne() inserts a single document into a collection.

The following example inserts a new document into the inventory collection. If the document does not specify an _id field, the Scala driver adds the _id field with an ObjectId value to the new document. See Insert Behavior.

db.inventory.insertOne(
{ item: "canvas", qty: 100, tags: ["cotton"], size: { h: 28, w: 35.5, uom: "cm" } }
)
Compass insert new document into collection
var document = new BsonDocument
{
{ "item", "canvas" },
{ "qty", 100 },
{ "tags", new BsonArray { "cotton" } },
{ "size", new BsonDocument { { "h", 28 }, { "w", 35.5 }, { "uom", "cm" } } }
};
collection.InsertOne(document);
result, err := coll.InsertOne(
context.TODO(),
bson.D{
{"item", "canvas"},
{"qty", 100},
{"tags", bson.A{"cotton"}},
{"size", bson.D{
{"h", 28},
{"w", 35.5},
{"uom", "cm"},
}},
})
Document canvas = new Document("item", "canvas")
.append("qty", 100)
.append("tags", singletonList("cotton"));
Document size = new Document("h", 28)
.append("w", 35.5)
.append("uom", "cm");
canvas.put("size", size);
Publisher<Success> insertOnePublisher = collection.insertOne(canvas);
Document canvas = new Document("item", "canvas")
.append("qty", 100)
.append("tags", singletonList("cotton"));
Document size = new Document("h", 28)
.append("w", 35.5)
.append("uom", "cm");
canvas.put("size", size);
collection.insertOne(canvas);
await db.inventory.insert_one(
{
"item": "canvas",
"qty": 100,
"tags": ["cotton"],
"size": {"h": 28, "w": 35.5, "uom": "cm"},
}
)
await db.collection('inventory').insertOne({
item: 'canvas',
qty: 100,
tags: ['cotton'],
size: { h: 28, w: 35.5, uom: 'cm' }
});
$db->coll("inventory")->insert_one(
{
item => "canvas",
qty => 100,
tags => ["cotton"],
size => { h => 28, w => 35.5, uom => "cm" }
}
);
$insertOneResult = $db->inventory->insertOne([
'item' => 'canvas',
'qty' => 100,
'tags' => ['cotton'],
'size' => ['h' => 28, 'w' => 35.5, 'uom' => 'cm'],
]);
db.inventory.insert_one(
{
"item": "canvas",
"qty": 100,
"tags": ["cotton"],
"size": {"h": 28, "w": 35.5, "uom": "cm"},
}
)
client[:inventory].insert_one({ item: 'canvas',
qty: 100,
tags: [ 'cotton' ],
size: { h: 28, w: 35.5, uom: 'cm' } })
collection.insertOne(
Document("item" -> "canvas", "qty" -> 100, "tags" -> Seq("cotton"), "size" -> Document("h" -> 28, "w" -> 35.5, "uom" -> "cm"))
).execute()

insertOne() returns a document that includes the newly inserted document's _id field value. For an example of a return document, see db.collection.insertOne() reference.

Note

MongoDB Compass generates the _id field and its value automatically. The generated ObjectId consists of a unique randomly generated hexadecimal value.

You can change this value prior to inserting your document so long as it remains unique and is a valid ObjectId. For more information on the _id field, see _id Field.

Collection.InsertOne function returns an instance of InsertOneResult whose InsertedID attribute contains the _id of the newly inserted document.

com.mongodb.client.MongoCollection.insertOne returns an instance of InsertOneResult. You can access the _id field of the inserted document by calling the getInsertedId() method on the result.

insert_one returns an instance of pymongo.results.InsertOneResult whose inserted_id field contains the _id of the newly inserted document.

insertOne() returns a promise that provides a result. The result.insertedId promise contains the _id of the newly inserted document.

Upon successful insert, the insert_one() method returns an instance of MongoDB::InsertOneResult whose inserted_id attribute contains the _id of the newly inserted document.

Upon successful insert, the insertOne() method returns an instance of MongoDB\\InsertOneResult whose getInsertedId() method returns the _id of the newly inserted document.

insert_one returns an instance of pymongo.results.InsertOneResult whose inserted_id field contains the _id of the newly inserted document.

Upon successful insert, the insert_one() method returns an instance of Mongo::Operation::Result, whose inserted_id attribute contains the _id of the newly inserted document.

Upon successful insert, the collection.insertOne() method returns an instance of collection.insertOne().results(); whose inserted_id attribute contains the _id of the newly inserted document.

To retrieve the document that you just inserted, query the collection:

db.inventory.find( { item: "canvas" } )
Query for matching documents in a collection

Specify a filter in the MongoDB Compass query bar and click Find to execute the query.

The above filter specifies that MongoDB Compass only return documents where the item field is equal to canvas.

For more information on the MongoDB Compass Query Bar, see the Compass Query Bar documentation.

var filter = Builders<BsonDocument>.Filter.Eq("item", "canvas");
var result = collection.Find(filter).ToList();
cursor, err := coll.Find(
context.TODO(),
bson.D{{"item", "canvas"}},
)
FindPublisher<Document> findPublisher = collection.find(eq("item", "canvas"));
FindIterable<Document> findIterable = collection.find(eq("item", "canvas"));
cursor = db.inventory.find({"item": "canvas"})
const cursor = db.collection('inventory').find({ item: 'canvas' });
$cursor = $db->coll("inventory")->find( { item => "canvas" } );
$cursor = $db->inventory->find(['item' => 'canvas']);
cursor = db.inventory.find({"item": "canvas"})
client[:inventory].find(item: 'canvas')
val observable = collection.find(equal("item", "canvas"))

Use the Select your language drop-down menu in the upper-right to set the language of the examples on this page.


New in version 3.2.

db.collection.insertMany() can insert multiple documents into a collection. Pass an array of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, MongoDB adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

IMongoCollection.InsertMany() can insert multiple documents into a collection. Pass an enumerable collection of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

Collection.InsertMany can insert multiple documents into a collection.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

com.mongodb.reactivestreams.client.MongoCollection.html.insertMany inserts the following documents with the Java Reactive Streams Driver:

{ item: "journal", qty: 25, tags: ["blank", "red"], size: { h: 14, w: 21, uom: "cm" } }
{ item: "mat", qty: 85, tags: ["gray"], size: { h: 27.9, w: 35.5, uom: "cm" } }
{ item: "mousepad", qty: 25, tags: ["gel", "blue"], size: { h: 19, w: 22.85, uom: "cm" } }

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

com.mongodb.client.MongoCollection.insertMany can insert multiple documents into a collection. Pass a list of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

motor.motor_asyncio.AsyncIOMotorCollection.insert_many can insert multiple documents into a collection. Pass an iterable of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the PyMongo driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

Collection.insertMany() can insert multiple documents into a collection. Pass an array of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the Node.js driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

MongoDB::Collection::insert_many() can insert multiple documents into a collection. Pass an array reference of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the Perl driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

MongoDB\\Collection::insertMany() can insert multiple documents into a collection. Pass an array of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the PHP driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

pymongo.collection.Collection.insert_many can insert multiple documents into a collection. Pass an iterable of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the PyMongo driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

Mongo::Collection#insert_many() can insert multiple documents into a collection. Pass an array of documents to the method.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the Ruby driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

New in version 3.2.

collection.insertMany() can insert multiple documents into a collection.

The following example inserts three new documents into the inventory collection. If the documents do not specify an _id field, the Scala driver adds the _id field with an ObjectId value to each document. See Insert Behavior.

db.inventory.insertMany([
{ item: "journal", qty: 25, tags: ["blank", "red"], size: { h: 14, w: 21, uom: "cm" } },
{ item: "mat", qty: 85, tags: ["gray"], size: { h: 27.9, w: 35.5, uom: "cm" } },
{ item: "mousepad", qty: 25, tags: ["gel", "blue"], size: { h: 19, w: 22.85, uom: "cm" } }
])
[
{ "item": "canvas", "qty": 100, "size": { "h": 28, "w": 35.5, "uom": "cm" }, "status": "A" },
{ "item": "journal", "qty": 25, "size": { "h": 14, "w": 21, "uom": "cm" }, "status": "A" },
{ "item": "mat", "qty": 85, "size": { "h": 27.9, "w": 35.5, "uom": "cm" }, "status": "A" },
{ "item": "mousepad", "qty": 25, "size": { "h": 19, "w": 22.85, "uom": "cm" }, "status": "P" },
{ "item": "notebook", "qty": 50, "size": { "h": 8.5, "w": 11, "uom": "in" }, "status": "P" },
{ "item": "paper", "qty": 100, "size": { "h": 8.5, "w": 11, "uom": "in" }, "status": "D" },
{ "item": "planner", "qty": 75, "size": { "h": 22.85, "w": 30, "uom": "cm" }, "status": "D" },
{ "item": "postcard", "qty": 45, "size": { "h": 10, "w": 15.25, "uom": "cm" }, "status": "A" },
{ "item": "sketchbook", "qty": 80, "size": { "h": 14, "w": 21, "uom": "cm" }, "status": "A" },
{ "item": "sketch pad", "qty": 95, "size": { "h": 22.85, "w": 30.5, "uom": "cm" }, "status": "A" }
]

For instructions on inserting documents using MongoDB Compass, see Insert Documents.

var documents = new BsonDocument[]
{
new BsonDocument
{
{ "item", "journal" },
{ "qty", 25 },
{ "tags", new BsonArray { "blank", "red" } },
{ "size", new BsonDocument { { "h", 14 }, { "w", 21 }, { "uom", "cm"} } }
},
new BsonDocument
{
{ "item", "mat" },
{ "qty", 85 },
{ "tags", new BsonArray { "gray" } },
{ "size", new BsonDocument { { "h", 27.9 }, { "w", 35.5 }, { "uom", "cm"} } }
},
new BsonDocument
{
{ "item", "mousepad" },
{ "qty", 25 },
{ "tags", new BsonArray { "gel", "blue" } },
{ "size", new BsonDocument { { "h", 19 }, { "w", 22.85 }, { "uom", "cm"} } }
},
};
collection.InsertMany(documents);
result, err := coll.InsertMany(
context.TODO(),
[]interface{}{
bson.D{
{"item", "journal"},
{"qty", int32(25)},
{"tags", bson.A{"blank", "red"}},
{"size", bson.D{
{"h", 14},
{"w", 21},
{"uom", "cm"},
}},
},
bson.D{
{"item", "mat"},
{"qty", int32(25)},
{"tags", bson.A{"gray"}},
{"size", bson.D{
{"h", 27.9},
{"w", 35.5},
{"uom", "cm"},
}},
},
bson.D{
{"item", "mousepad"},
{"qty", 25},
{"tags", bson.A{"gel", "blue"}},
{"size", bson.D{
{"h", 19},
{"w", 22.85},
{"uom", "cm"},
}},
},
})
Document journal = new Document("item", "journal")
.append("qty", 25)
.append("tags", asList("blank", "red"));
Document journalSize = new Document("h", 14)
.append("w", 21)
.append("uom", "cm");
journal.put("size", journalSize);
Document mat = new Document("item", "mat")
.append("qty", 85)
.append("tags", singletonList("gray"));
Document matSize = new Document("h", 27.9)
.append("w", 35.5)
.append("uom", "cm");
mat.put("size", matSize);
Document mousePad = new Document("item", "mousePad")
.append("qty", 25)
.append("tags", asList("gel", "blue"));
Document mousePadSize = new Document("h", 19)
.append("w", 22.85)
.append("uom", "cm");
mousePad.put("size", mousePadSize);
Publisher<Success> insertManyPublisher = collection.insertMany(asList(journal, mat, mousePad));
Document journal = new Document("item", "journal")
.append("qty", 25)
.append("tags", asList("blank", "red"));
Document journalSize = new Document("h", 14)
.append("w", 21)
.append("uom", "cm");
journal.put("size", journalSize);
Document mat = new Document("item", "mat")
.append("qty", 85)
.append("tags", singletonList("gray"));
Document matSize = new Document("h", 27.9)
.append("w", 35.5)
.append("uom", "cm");
mat.put("size", matSize);
Document mousePad = new Document("item", "mousePad")
.append("qty", 25)
.append("tags", asList("gel", "blue"));
Document mousePadSize = new Document("h", 19)
.append("w", 22.85)
.append("uom", "cm");
mousePad.put("size", mousePadSize);
collection.insertMany(asList(journal, mat, mousePad));
await db.inventory.insert_many(
[
{
"item": "journal",
"qty": 25,
"tags": ["blank", "red"],
"size": {"h": 14, "w": 21, "uom": "cm"},
},
{
"item": "mat",
"qty": 85,
"tags": ["gray"],
"size": {"h": 27.9, "w": 35.5, "uom": "cm"},
},
{
"item": "mousepad",
"qty": 25,
"tags": ["gel", "blue"],
"size": {"h": 19, "w": 22.85, "uom": "cm"},
},
]
)
await db.collection('inventory').insertMany([
{
item: 'journal',
qty: 25,
tags: ['blank', 'red'],
size: { h: 14, w: 21, uom: 'cm' }
},
{
item: 'mat',
qty: 85,
tags: ['gray'],
size: { h: 27.9, w: 35.5, uom: 'cm' }
},
{
item: 'mousepad',
qty: 25,
tags: ['gel', 'blue'],
size: { h: 19, w: 22.85, uom: 'cm' }
}
]);
$db->coll("inventory")->insert_many(
[
{
item => "journal",
qty => 25,
tags => [ "blank", "red" ],
size => { h => 14, w => 21, uom => "cm" }
},
{
item => "mat",
qty => 85,
tags => ["gray"],
size => { h => 27.9, w => 35.5, uom => "cm" }
},
{
item => "mousepad",
qty => 25,
tags => [ "gel", "blue" ],
size => { h => 19, w => 22.85, uom => "cm" }
}
]
);
$insertManyResult = $db->inventory->insertMany([
[
'item' => 'journal',
'qty' => 25,
'tags' => ['blank', 'red'],
'size' => ['h' => 14, 'w' => 21, 'uom' => 'cm'],
],
[
'item' => 'mat',
'qty' => 85,
'tags' => ['gray'],
'size' => ['h' => 27.9, 'w' => 35.5, 'uom' => 'cm'],
],
[
'item' => 'mousepad',
'qty' => 25,
'tags' => ['gel', 'blue'],
'size' => ['h' => 19, 'w' => 22.85, 'uom' => 'cm'],
],
]);
db.inventory.insert_many(
[
{
"item": "journal",
"qty": 25,
"tags": ["blank", "red"],
"size": {"h": 14, "w": 21, "uom": "cm"},
},
{
"item": "mat",
"qty": 85,
"tags": ["gray"],
"size": {"h": 27.9, "w": 35.5, "uom": "cm"},
},
{
"item": "mousepad",
"qty": 25,
"tags": ["gel", "blue"],
"size": {"h": 19, "w": 22.85, "uom": "cm"},
},
]
)
client[:inventory].insert_many([{ item: 'journal',
qty: 25,
tags: ['blank', 'red'],
size: { h: 14, w: 21, uom: 'cm' }
},
{ item: 'mat',
qty: 85,
tags: ['gray'],
size: { h: 27.9, w: 35.5, uom: 'cm' }
},
{ item: 'mousepad',
qty: 25,
tags: ['gel', 'blue'],
size: { h: 19, w: 22.85, uom: 'cm' }
}
])
collection.insertMany(Seq(
Document("item" -> "journal", "qty" -> 25, "tags" -> Seq("blank", "red"), "size" -> Document("h" -> 14, "w" -> 21, "uom" -> "cm")),
Document("item" -> "mat", "qty" -> 85, "tags" -> Seq("gray"), "size" -> Document("h" -> 27.9, "w" -> 35.5, "uom" -> "cm")),
Document("item" -> "mousepad", "qty" -> 25, "tags" -> Seq("gel", "blue"), "size" -> Document("h" -> 19, "w" -> 22.85, "uom" -> "cm"))
)).execute()

insertMany() returns a document that includes the newly inserted documents _id field values. See the reference for an example.

To retrieve the inserted documents, query the collection:

To retrieve the inserted documents, query the collection:

To retrieve the inserted documents, query the collection:

com.mongodb.reactivestreams.client.MongoCollection.html.insertMany returns a Publisher object. The Publisher inserts the document into a collection when subscribers request data.

To retrieve the inserted documents, query the collection:

To retrieve the inserted documents, query the collection:

insert_many returns an instance of pymongo.results.InsertManyResult whose inserted_ids field is a list containing the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

insertMany() returns a promise that provides a result. The result.insertedIds field contains an array with the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

Upon successful insert, the insert_many() method returns an instance of MongoDB::InsertManyResult whose inserted_ids attribute is a list containing the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

Upon successful insert, the insertMany() method returns an instance of MongoDB\\InsertManyResult whose getInsertedIds() method returns the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

insert_many returns an instance of pymongo.results.InsertManyResult whose inserted_ids field is a list containing the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

Upon successful insert, the insert_many() method returns an instance of Mongo::BulkWrite::Result whose inserted_ids attribute is a list containing the _id of each newly inserted document.

To retrieve the inserted documents, query the collection:

Upon successful insert, the insertMany() method returns an Observable with a type parameter indicating when the operation has completed or with either a com.mongodb.DuplicateKeyException or com.mongodb.MongoException.

To retrieve the inserted documents, query the collection:

db.inventory.find( {} )
Compass select all documents in collection
var filter = Builders<BsonDocument>.Filter.Empty;
var result = collection.Find(filter).ToList();
cursor, err := coll.Find(
context.TODO(),
bson.D{},
)
FindPublisher<Document> findPublisher = collection.find(new Document());
FindIterable<Document> findIterable = collection.find(new Document());
cursor = db.inventory.find({})
const cursor = db.collection('inventory').find({});
$cursor = $db->coll("inventory")->find( {} );
$cursor = $db->inventory->find([]);
cursor = db.inventory.find({})
client[:inventory].find({})
var findObservable = collection.find(Document())

If the collection does not currently exist, insert operations will create the collection.

In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the MongoDB driver automatically generates an ObjectId for the _id field.

This also applies to documents inserted through update operations with upsert: true.

All write operations in MongoDB are atomic on the level of a single document. For more information on MongoDB and atomicity, see Atomicity and Transactions

With write concerns, you can specify the level of acknowledgement requested from MongoDB for write operations. For details, see Write Concern.

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