Redis cache implementation using express js and mongoose

Question

I am beginner in redis cache. I have an application in express js , uses mongoose for mongo db. There are two collections named users and payments.

Here I used join of both collection while I fetch data from mongo db . Here I used mongoose.

Now I want to implement redis caching. As I know redis works based on key value pair. I need guideline.

• How can I make join query to get both collection data ?
• Besides If I make any update on collection data then how it will reflect?
• May I use mongoose as well on redis ?
• Where may I get details / learn of that ?

Please suggest me best practices.