Automatically parse some fields to string on mongoose?

Mongoose allows a set property, in your Schema, that will be used to alter the value before insertion.

You could use this set property to "stringify" your values.

{
  name: { type: String, required: true },
  value: { type: String, required: true, set: (val) => val.toString()},
  other: {
    otherValue: { type: String, required: true, set: (val) => val.toString() },
  }
}