Add go-pg integration example (#12)

examples/go_pg_integration.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/bluele/factory-go/factory"
+	"github.com/go-pg/pg"
+	"github.com/go-pg/pg/orm"
+)
+
+type Group struct {
+	ID   int
+	Name string
+}
+
+type User struct {
+	ID    int
+	Name  string
+	Group *Group
+}
+
+var UserFactory = factory.NewFactory(
+	&User{},
+).SeqInt("ID", func(n int) (interface{}, error) {
+	return n, nil
+}).Attr("Name", func(args factory.Args) (interface{}, error) {
+	user := args.Instance().(*User)
+	return fmt.Sprintf("user-%d", user.ID), nil
+}).OnCreate(func(args factory.Args) error {
+	tx := args.Context().Value("tx").(*pg.Tx)
+	return tx.Insert(args.Instance())
+}).SubFactory("Group", GroupFactory)
+
+var GroupFactory = factory.NewFactory(
+	&Group{},
+).SeqInt("ID", func(n int) (interface{}, error) {
+	return n, nil
+}).Attr("Name", func(args factory.Args) (interface{}, error) {
+	group := args.Instance().(*Group)
+	return fmt.Sprintf("group-%d", group.ID), nil
+}).OnCreate(func(args factory.Args) error {
+	tx := args.Context().Value("tx").(*pg.Tx)
+	return tx.Insert(args.Instance())
+})
+
+func createTestSchema(db *pg.DB) error {
+	tables := []interface{}{
+		&Group{},
+		&User{},
+	}
+	for _, table := range tables {
+		err := db.DropTable(table, &orm.DropTableOptions{
+			IfExists: true,
+			Cascade:  true,
+		})
+		if err != nil {
+			return err
+		}
+
+		err = db.CreateTable(table, nil)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func openDB() *pg.DB {
+	db := pg.Connect(&pg.Options{
+		User: "postgres",
+	})
+
+	err := createTestSchema(db)
+	if err != nil {
+		panic(err)
+	}
+
+	return db
+}
+
+func main() {
+	db := openDB()
+	for i := 0; i < 3; i++ {
+		tx, err := db.Begin()
+		if err != nil {
+			panic(err)
+		}
+
+		ctx := context.WithValue(context.Background(), "tx", tx)
+		v, err := UserFactory.CreateWithContext(ctx)
+		if err != nil {
+			panic(err)
+		}
+		user := v.(*User)
+		fmt.Println(user, *user.Group)
+		tx.Commit()
+	}
+}