Performing data manipulations is great, but in order to develop complex applications, you will need your ODM module to do more. Luckily, Mongoose supports various other features that help you safely model your documents and keep your data consistent.
Defining default field values is a common feature for data-modeling frameworks. You can add this functionality directly to your application's logic layer, but that would be messy and is generally a bad practice. Mongoose offers to define the default values at the schema level, helping you organize your code better and guaranteeing your documents' validity.
Let's say you want to add a created date field to your UserSchema. The created date field should be initialized at creation time and the time at which the user document was initially created should be saved—a perfect example of when you can utilize a default value. To do this, you'll have to change your UserSchema; so, go back to your app...