GORM model with different attributes

sample-any.go

package main

import (
	"gorm.io/gorm"
	"log"
)
import "gorm.io/driver/postgres"

type StaffAttribute struct {
	Department string `gorm:"type:string"`
	Role       string `gorm:"type:string"`
}

type BotAttribute struct {
	DisplayName string `gorm:"type:string"`
	Permission  string `gorm:"type:string"`
}

type User struct {
	ID         string `gorm:"type:serial"`
	Username   string `gorm:"type:string"`
	Type       string `gorm:"type:string"`
	Attributes any    `gorm:"serializer:json"`
}

func (u *User) AfterFind(tx *gorm.DB) (err error) {
	parsedAttributes := u.Attributes.(map[string]interface{})
	if u.Type == "staff" {
		u.Attributes = StaffAttribute{
			Department: parsedAttributes["Department"].(string),
			Role:       parsedAttributes["Role"].(string),
		}
	} else if u.Type == "bot" {
		u.Attributes = BotAttribute{
			DisplayName: parsedAttributes["DisplayName"].(string),
			Permission:  parsedAttributes["Permission"].(string),
		}
	}
	return
}

func main() {
	dsn := "host=127.0.0.1 user=user password=secret dbname=db"

	// Connection.
	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
	if err != nil {
		log.Fatalf("Database connection failed: %s", err)
	}

	// Migration.
	_ = db.AutoMigrate(&User{})

	// Data insertion.
	db.Create(&User{
		Username: "Mort",
		Type:     "staff",
		Attributes: StaffAttribute{
			Department: "WS",
			Role:       "Developer",
		},
	})
	db.Create(&User{
		Username: "Cmd",
		Type:     "bot",
		Attributes: BotAttribute{
			Permission:  "+w",
			DisplayName: "Command",
		},
	})

	// Fetch data.
	var staffUser User
	db.First(&staffUser, 1)
	log.Printf("%#v\n", staffUser.Attributes.(StaffAttribute).Department)

	var botUser User
	db.First(&botUser, 2)
	log.Printf("%#v\n", botUser)
	log.Printf("%#v\n", botUser.Attributes.(BotAttribute).DisplayName)
}

sample-generic.go

package main

import (
	"gorm.io/gorm"
	"log"
)
import "gorm.io/driver/postgres"

type StaffAttribute struct {
	Department string `gorm:"type:string"`
	Role       string `gorm:"type:string"`
}

type BotAttribute struct {
	DisplayName string `gorm:"type:string"`
	Permission  string `gorm:"type:string"`
}

type UserAttribute interface {
	StaffAttribute | BotAttribute
}

type User[T UserAttribute] struct {
	ID       string `gorm:"type:serial"`
	Username string `gorm:"type:string"`
	Type     string `gorm:"type:string"`
	Attributes T `gorm:"serializer:json"`
}

func (User[T]) TableName() string {
	return "users"
}

func main() {
	dsn := "host=127.0.0.1 user=user password=secret dbname=db"

	// Connection.
	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
	if err != nil {
		log.Fatalf("Database connection failed: %s", err)
	}

	// Migration.
	_ = db.AutoMigrate(&User[StaffAttribute]{})

	// Data insertion.
	db.Create(&User[StaffAttribute]{
		Username: "Mort",
		Type:     "staff",
		Attributes: StaffAttribute{
			Department: "WS",
			Role:       "Developer",
		},
	})
	db.Create(&User[BotAttribute]{
		Username: "Cmd",
		Type:     "bot",
		Attributes: BotAttribute{
			Permission:  "+w",
			DisplayName: "Command",
		},
	})

	// Fetch data.
	var staffUser User[StaffAttribute]
	db.First(&staffUser, 1)
	log.Printf("%#v\n", staffUser)

	var botUser User[BotAttribute]
	db.First(&botUser, 2)
	log.Printf("%#v\n", botUser)
}

sample.go

package main

import (
	"gorm.io/gorm"
	"log"
)
import "gorm.io/driver/postgres"

type User struct {
	ID         string         `gorm:"type:serial"`
	Username   string         `gorm:"type:string"`
	Type       string         `gorm:"type:string"`
	Attributes map[string]any `gorm:"serializer:json"`
}

type StaffAttribute struct {
	Department string `gorm:"type:string"`
	Role       string `gorm:"type:string"`
}
type Staff struct {
	User
	Attributes StaffAttribute `gorm:"serializer:json"`
}

func (Staff) TableName() string {
	return "users"
}

type BotAttribute struct {
	DisplayName string `gorm:"type:string"`
	Permission  string `gorm:"type:string"`
}
type Bot struct {
	User
	Attributes BotAttribute `gorm:"serializer:json"`
}

func (Bot) TableName() string {
	return "users"
}

func main() {
	dsn := "host=127.0.0.1 user=user password=secret dbname=db"

	// Connection.
	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
	if err != nil {
		log.Fatalf("Database connection failed: %s", err)
	}

	// Migration.
	_ = db.AutoMigrate(&User{})

	// Data insertion.
	db.Create(&Staff{
		User: User{
			Username: "Mort",
			Type:     "staff",
		},
		Attributes: StaffAttribute{
			Department: "WS",
			Role:       "Developer",
		},
	})
	db.Create(&Bot{
		User: User{
			Username: "Cmd",
			Type:     "bot",
		},
		Attributes: BotAttribute{
			Permission:  "+w",
			DisplayName: "Command",
		},
	})

	// Fetch data.
	var staffUser Staff
	db.First(&staffUser, 1)
	log.Printf("%#v\n", staffUser)

	var botUser Bot
	db.First(&botUser, 2)
	log.Printf("%#v\n", botUser)
}