(A draft StackOverlow questioned that I answered for myself)
Draft question
I am using mongosh version 2.26 on iTerm2 (Build 3.5.0) on a Mac.
I am starting to explore MongoDB with the aim of setting up a MERN website.
When I run mongosh, the Mongo shell correctly opens.
Within the Mongo shell, I switch to and create a new db, e.g. one called random, by > use random.
$ show collections correctly shows no collection.
I then run db.new.insertOne({name: "name"}). A document is correctly created under the new collection.
But when I run db.hello.insertOne({name: "name"}), I get the error
TypeError: db.hello.insertOne is not a function
This is particularly bizarre because if I run db.createCollection("hello"), I do succeed in creating a collection called “hello”.
MongoDB documentation provides,
Restriction on Collection Names
Collection names should begin with an underscore or a letter character, and cannot:
- contain the $.
- be an empty string (e.g. “”).
- ontain the null character.
- begin with the system. prefix. (Reserved for internal use.)
If your collection name includes special characters, such as the underscore character, or begins with numbers, then to access the collection use the db.getCollection() method in mongosh or a similar method for your driver.
I don’t see how I am in breach.
I also don’t think the issue is I have a collection in another database called “hello”. I made another db called “new”, and made a collection within it also called “new”. No problems there.
So what might explain the titled error?
Answer
Improbable as it may sound: “hello” is actually a standalone method in MongoDB.
This can be shown if you run db.hello().