So I am using this template: https://github.com/vercel-labs/ai-chatbot

Id make a root /db dir. choosing between clients is really your call.

Mongoose is usually a bit heavier, not ideal if youre hosting serverless

I personally go for mongodb (the official driver) with typescript typings but mongoose has some benefits like middlewares and hooks that allow pre and post processing. Looking into prisma is also a good idea but a bit time consuming to learn

For the template I am referring to, it seems that all of it is using edge runtime. And I tried to use MongoDB-client. But I found that MongoDB-client cannot be used because Edge runtime doesn't support some of its NodeJS modules.

ive seen people opt for prisma when using edge

havent been able to personally give it a go tho

If I put into root/db/db.js, how can I make API request to the database? I thought that I would have to put the db.js in API folder and then call fetch request from frontend UI code.

in a nodejs environment, each api request would initiate a new instance of the function so you have to initiate the db client within the function using it. (which is why at some point caching the connection or using a proxy is necessary for heavy traffic) This is a good walkthrough https://www.mongodb.com/developer/languages/javascript/nextjs-with-mongodb/.

when using the edge runtime env i think prisma proxy is the way to go.

thanx!!!