FMap is a simple library for working with structs as map of fields. Switch case and reflect based.

FMap creates new map with filed names as key and with fmap.Field(reflect.StructField) values. This is unsafe library, be careful while use.

fmap.Field has 3 advanced methods:

Get[T any]() any
Set(obj any, val any)
GetPtr(obj any) any

where the obj should be not nil pointer to struct.
Get[T any]() any - return expected typed value as interface{}.
Set(obj any, val any) - val expected typed value to set, {}interface can be used.
GetPtr(obj any) any - return expected typed value pointer to struct field as interface{}.

package main

import (
	"time"
	"fmt"

	"github.com/insei/fmap"
)

type City struct {
	Name string
}

type People struct {
	Name     string
	Age      uint8
	Birthday time.Time
	City City
}

func main() {
	p := &People{}
	fields := fmap.Get[People]() // or fmap.GetFrom(p)
	fields["Name"].Set(p, "Test")
	fields["Age"].Set(p, uint8(5))
	fields["Birthday"].Set(p, time.Now())
	fields["City.Name"].Set(p, "DefaultCity")
	fmt.Print(*p)
}

More examples in fields_test.go, like slice fields, nested structs, pointers etc.