generic shared data

shared.go

package main

import (
	"fmt"
	"reflect"
)

func main() {
	render(MyData{Foo: "bar"})
}

type MyData struct {
	Shared
	Foo string
}

func render[T any](data T) {
	if val := reflect.ValueOf(&data); val.IsValid() && val.Kind() == reflect.Pointer {
		fmt.Println("&data is pointer")
		if val := val.Elem(); val.IsValid() && val.Kind() == reflect.Struct {
			fmt.Println("data is struct")
			if val := val.FieldByName("Shared"); val.IsValid() && val.CanSet() && val.Type() == reflect.TypeOf(Shared{}) {
				fmt.Println("data has shared data")
				val.Set(reflect.ValueOf(Shared{
					Authenticated: true,
					User: User{
						ID:       "1",
						Email:    "[email protected]",
						Username: "user",
					},
				}))
			}
		}
	}

	fmt.Printf("data: %+v\n", data)
  // Output: data: {Shared:{Authenticated:true User:{ID:1 Email:[email protected] Username:user}} Foo:bar}
}

type Shared struct {
	Authenticated bool
	User          User
}

type User struct {
	ID       string
	Email    string
	Username string
}