This is how to do upserting in MongoDB

For a full overview of MongoDB and all my posts on it, check out my overview.

Upserting is a database concept that combines inserting and updating that MongoDB supports. To perform an upsert during an update operation, you must pass an additional argument to the update, updateOne, or updateMany methods.

With the given data inserted in a collection called users:

db.users.insertMany([
    {
        _id: 1,
        name: "John Doe",
        email: "[e-mail]",
        admin: true
    },
    {
        _id: 2,
        name: "Jane Doe",
        email: "[e-mail]",
        admin: true
    },
    {
        _id: 3,
        name: "Billy Bob",
        email: "[e-mail]",
        admin: false
    },
    {
        _id: 4
        name: "Steve Stevenson",
        email: "[e-mail]",
        admin: true
    },
])

If the following command is used:

db.users.updateOne({_id: 5}, {$set: {admin: true}})

It won't do anything as there is no document matching the query of _id = 5.

If upserting is enabled:

db.users.updateOne(
    {_id: 5},
    { $set: { admin: true } },
    { upsert: true }
)

Since there is no document matching the query, a new document is inserting using the given _id and the result of the update operators.

Use the find method to read data back out of MongoDB to check the collection:

db.users.find()

Will yield:

{
    _id: 1,
    name: "John Doe",
    email: "[e-mail]",
    admin: true
},
{
    _id: 2,
    name: "Jane Doe",
    email: "[e-mail]",
    admin: true
},
{
    _id: 3,
    name: "Billy Bob",
    email: "[e-mail]",
    admin: false
},
{
    _id: 4
    name: "Steve Stevenson",
    email: "[e-mail]",
    admin: true
},
{
    _id: 5
    admin: true
}