vapor-docs/3.0/docs/routing/parameters.md

Parameters

Parameters are a registered type that can be initialized from a String.

They can be part of a Route, and be extracted from Requests that are called in that Route.

Creating custom parameters

To create a custom parameter type, simply conform to Parameter and implement the conversion function make and a unique slug.

In this example, the User class will be initialized from a parameter that represents it's identifier.

class User : Parameter {
  static var uniqueSlug = "my-app:user"

  static func make(for parameter: String, in request: Request) throws -> User {
    // Fetches the user from MySQL
    let user =
  }
}

TODO!!!