Schema with timeseries and autoCreate: false does not create a timeseries collection

[AnderbergE]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

8.18.0

Node.js version

24

MongoDB server version

7.0.11

Typescript version (if applicable)

No response

Description

A schema that specifies both options timeseries and autoCreate: false does not create a timeseries collection.
This has not been fixed on the latest version. I have not tested older versions.
Please note that the documentation uses autoCreate: false: https://mongoosejs.com/docs/guide.html#timeseries
This may be related to this issue from 2022: #11916

Steps to Reproduce

This schema will create a type: 'collection' in MongoDB when the first document is inserted:

new Schema({
  meta: {
    devId: { type: String, required: true },
  },
  ts: { type: Date, required: true },
  count: { type: Number },
}, {
  timeseries: {
    timeField: 'ts',
    metaField: 'meta',
    granularity: 'minutes',
  },
  autoCreate: false,
})

This schema (without autoCreate) will create a type: 'timeseries' in MongoDB after connecting to db:

new Schema({
  meta: {
    devId: { type: String, required: true },
  },
  ts: { type: Date, required: true },
  count: { type: Number },
}, {
  timeseries: {
    timeField: 'ts',
    metaField: 'meta',
    granularity: 'minutes',
  },
})

Expected Behavior

When creating a model with schema that specifies timeseries, I expect that the collection in the MongoDB server is created as a timeseries type. If this cannot be solved, then I expect the documentation to write about it.

[vkarpov15]

I added a note to the documentation - you need to explicitly create the collection using createCollection(), or leave autoCreate: true and let Mongoose create the collection for you. If you insert a document into a collection that doesn't exist, MongoDB will create a collection with default options, no timeseries.