Adding data to a MongoDB database (part 1)

The insertOne() method allows you to insert a single document into a collection. The insertOne() method has the following syntax:

db.collection.insertOne(
   <document>,
   { writeConcern: <document>}
)

The insertOne() method accepts two arguments:

• document is a document that you want to insert into the collection. The document argument is required.
• writeConcern is an optional argument that describes the level of acknowledgment requested from MongoDB for insert operation to a standalone MongoDB server or to shared clusters. We’ll discuss the writeConcern another tutorial.

The insertOne() method returns a document that contains the following fields:

• acknowledged is a boolean value. It is set to true if the insert executed with write concern or false if the write concern was disabled.
• insertedId stores the value of _id field of the inserted document.

Example:

First, you need to launch the mongo shell and connect it to the bookdb database: mongosh bookdb

Insert a document without an _id field example:

db.books.insertOne({ 
    title: 'MongoDB insertOne',
    isbn: '0-7617-6154-3'
});

To select the document that you have inserted, you can use the find() method like this: db.books.find()

Insert a document with an _id field example:

db.books.insertOne({
   _id: 1,
   title: "Mastering Big Data",
   isbn: "0-9270-4986-4"
});

The following example attempts to insert another document whose _id field already exists into the books collection:

db.books.insertOne({
   _id: 1,
   title: "MongoDB for JS Developers",
   isbn: "0-4925-3790-9"
});

Since the _id: 1 already exists, MongoDB threw the following exception:

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