Is data communication between databases possible in MongoDB?

Question

MongoDB

Good time of the day. Don't take it as a stupid question, but whatever. On the mongodb server, I created several databases:
1) todos (used to store tasks) 2) users (used to store user data)
The todos database has a collection of tasks in the document, the owner field is stored which I need to identify the user who created the task. At the same time, a collection with a document containing the ObjectId("56c658bbcdc91848503259f5") field is stored in the users database. How can I link these two databases together so that when I search, I can find all the tasks of the user ObjectId("56c658bbcdc91848503259f5") I get all the documents from the todos database that the user created with this id? Thanks in advance for your replies. I myself understand that I'm a fool, but I just started learning mongo with a node :)

Answer 1

in order to find all the tasks of the user ObjectId("56c658bbcdc91848503259f5") with a search query, should I display all the documents from the todos database that the user created with this id? Thanks in advance for your replies

It doesn't matter where the users collection is, it may not exist at all, but you will still filter by ID in the query.

Answer 2

That's why take a NoSQL database, and then ask how to do things typical for relational databases here.
Connections are necessary - take some postgresql. Or change the scheme and store tasks together with the user in 1 document. Why use the tool for other purposes?
But if you are already impatient, then read here . I don’t know if there are joins at the DB level in Mongo, but if so, they can be done programmatically in 2 queries.