main.go

package main

import (
	"crypto/rand"
	"fmt"
	"log"
	"math/big"

	"github.com/jinzhu/gorm"
	_ "github.com/lib/pq"
)

type Countdown struct {
	ID   int
	Name string

	OwnerID   int
	OwnerType string
}

type ShopCountdown struct {
	ID   int
	Name string

	Countdowns []*Countdown `gorm:"polymorphic:Owner;"`
}

func main() {
	db, err := gorm.Open("postgres", "host=/tmp database=test")
	if err != nil {
		log.Fatalln(err)
	}
	defer db.Close()

	db.LogMode(true)
	db.AutoMigrate(&Countdown{}, &ShopCountdown{})

	//if err := create(db); err != nil {
	//	log.Fatalln(err)
	//}
	if err := load(db); err != nil {
		log.Fatalln(err)
	}
}

func create(db *gorm.DB) error {
	sc := &ShopCountdown{Name: "Mein geiler Shop"}
	if err := db.Preload("Countdowns").FirstOrCreate(sc, sc).Error; err != nil {
		return err
	}

	randBigInt, err := rand.Int(rand.Reader, big.NewInt(1000))
	if err != nil {
		return err
	}

	log.Println("shop loaded: ", sc)
	sc.Countdowns = append(sc.Countdowns, &Countdown{Name: fmt.Sprintf("CD %d", randBigInt.Int64())})

	if err := db.Save(sc).Error; err != nil {
		return err
	}

	log.Println("shop saved: ", sc)

	return nil
}

func load(db *gorm.DB) error {
	sc := &ShopCountdown{Name: "Mein geiler Shop"}
	if err := db.Model(sc).Where(sc).Preload("Countdowns").First(sc).Error; err != nil {
		return err
	}
	log.Println(sc)
	return nil
}