Mongoose is one of the best ODMs for MongoDB. Mongoose provides a straight-forward, schema-based solution to modeling your application data and includes built-in type casting, validation, query building, business logic hooks and more, out of the box. Mongoose does not require a specific structure of your project files. This is great but it always rises a common question on how to use a library within a project in a proper way. We do not want to manually figure the right way on how to split the code into multiple files every time we start a new Mongoose project. Things can be quite complicated especially when dealing with multiple database instances.