Explore Developer Center's New Chatbot! MongoDB AI Chatbot can be accessed at the top of your navigation to answer all your MongoDB questions.

Learn why MongoDB was selected as a leader in the 2024 Gartner® Magic Quadrant™
MongoDB Developer
Developer Topics
chevron-right
Products
chevron-right
MongoDB
chevron-right

Document Enrichment and Schema Updates

Jesse Hall2 min read • Published Jul 22, 2021 • Updated Aug 13, 2024
Facebook Icontwitter iconlinkedin icon
Rate this tutorial
star-empty
star-empty
star-empty
star-empty
star-empty
So your business needs have changed and there’s additional data that needs to be stored within an existing dataset. Fear not! With MongoDB, this is no sweat.
In this article, I’ll show you how to quickly add and populate additional fields into an existing database collection.

The Scenario

Let’s say you have a “Netflix” type application and you want to allow users to see which movies they have watched. We’ll use the sample_mflix database from the sample datasets available in a MongoDB Atlas cluster.
Here is the existing schema for the user collection in the sample_mflix database:
1{
2 _id: ObjectId(),
3 name: <string>,
4 email: <string>,
5 password: <string>
6}

The Solution

There are a few ways we could go about this. Since MongoDB has a flexible data model, we can just add our new data into existing documents.
In this example, we are going to assume that we know the user ID. We’ll use updateOne and the $addToSet operator to add our new data.
1const { db } = await connectToDatabase();
2const collection = await db.collection(“users”).updateOne(
3 { _id: ObjectID(“59b99db9cfa9a34dcd7885bf”) },
4 {
5 $addToSet: {
6 moviesWatched: {
7 <movieId>,
8 <title>,
9 <poster>
10 }
11 }
12 }
13);
The $addToSet operator adds a value to an array avoiding duplicates. If the field referenced is not present in the document, $addToSet will create the array field and enter the specified value. If the value is already present in the field, $addToSet will do nothing.
Using $addToSet will prevent us from duplicating movies when they are watched multiple times.

The Result

Now, when a user goes to their profile, they will see their watched movies.
But what if the user has not watched any movies? The user will simply not have that field in their document.
I’m using Next.js for this application. I simply need to check to see if a user has watched any movies and display the appropriate information accordingly.
1{ moviesWatched
2 ? "Movies I've Watched"
3 : "I have not watched any movies yet :("
4}

Conclusion

Because of MongoDB’s flexible data model, we can have multiple schemas in one collection. This allows you to easily update data and fields in existing schemas.
If you would like to learn more about schema validation, take a look at the Schema Validation documentation.
I’d love to hear your feedback or questions. Let’s chat in the MongoDB Community.

Facebook Icontwitter iconlinkedin icon
Rate this tutorial
star-empty
star-empty
star-empty
star-empty
star-empty
Related
Code Example

Cinema: Example Go Microservices Application


Sep 11, 2024 | 0 min read
News & Announcements

Introducing a New MongoDB Aggregations Book


Sep 23, 2022 | 1 min read
News & Announcements

Improved Error Messages for Schema Validation in MongoDB 5.0


Jun 14, 2023 | 10 min read
Tutorial

Confessions of a PyMongoArrowholic: Using Atlas Vector Search and PyMongoArrow to Semantically Search Through Luxury Fashion Items


Aug 09, 2024 | 9 min read