This is super useful for implementing a generic cascading soft delete in my application, where I am managing soft deletion and reference management in separate plugins.

This would also allow me to extend an existing plugin without breaking the base version. Cool!

This turned out to not be the case! On a whim, I tried passing "deleteOne" to the middleware function post() with a callback, and it worked!

Mongoose automagically took up the name of my instance method and enabled middleware on it. From what I can tell, this is not mentioned in the documentation.

I wanted to trigger some middleware when softDelete() was called. The Mongoose documentation lists the strings that can be passed to pre/post -- like the built-ins save and find.

Cursory research seemed to suggest that this list was not extendable and I'd have to handle this without middleware.

I'm writing middleware inside Mongoose plugins. Plugins can also add static and instance methods to Schemas.

For example, I define `schema.methods.softDelete = function(){}` as an instance method which sets the `deleted` property of a document (a Model instance) to true.

Each query type also comes extendable middleware, so you can define code that runs before (pre) or after (post) every query of a specific type.

So, by doing `schema.post("find", function(){})`, you can define a function that runs every after each find() query on a particular Schema (e.g. a User).