added pg db client and using it in another example

Author: Lairon Acosta Guardias

example2/example2.go

@@ -0,0 +1,127 @@
+package main
+
+import (
+	"fmt"
+	"github.com/Lairon/pg-db-go/pgdb"
+	"github.com/go-pg/pg/v10"
+	"github.com/go-pg/pg/v10/orm"
+)
+
+type User struct {
+	ID     int64
+	Name   string
+	Emails []string
+}
+
+type Book struct {
+	ID       int64
+	Title    string
+	ReaderID int64
+	Reader   *User `pg:"rel:has-one"`
+}
+
+type PgClient struct {
+	db *pg.DB
+}
+
+func main() {
+	client := NewPgClient()
+	defer client.db.Close()
+
+	client.createSchemeInsertSelect()
+}
+
+func NewPgClient() *PgClient {
+	return &PgClient{
+		db: pgdb.NewPgDB(&pg.Options{
+			User:     "postgres",
+			Password: "postgres",
+			Database: "pg-db-go",
+		}),
+	}
+}
+
+func (c *PgClient) createSchemeInsertSelect() {
+
+	db := c.db
+	err := c.CreateTable()
+	if err != nil {
+		panic(err)
+	}
+
+	user1 := User{
+		Name:   "admin",
+		Emails: []string{"admin1@admin", "admin2@admin"},
+	}
+	_, err = db.Model(&user1).Insert()
+	if err != nil {
+		panic(err)
+	}
+
+	user2 := User{
+		Name:   "root",
+		Emails: []string{"root1@admin", "root2@admin"},
+	}
+	_, err = db.Model(&user2).Insert()
+	if err != nil {
+		panic(err)
+	}
+
+	book1 := Book{
+		Title:    "PabloC",
+		ReaderID: user1.ID,
+	}
+	_, err = db.Model(&book1).Insert()
+	if err != nil {
+		panic(err)
+	}
+
+	//select user by pk
+	user := User{
+		ID: user1.ID,
+	}
+	err = db.Model(&user).WherePK().Select()
+	if err != nil {
+		panic(err)
+	}
+
+	// Select all users.
+	var users []User
+	err = db.Model(&users).Select()
+	if err != nil {
+		panic(err)
+	}
+
+	// Select book and associated reader in one query.
+	book := Book{}
+	err = db.Model(&book).
+		Relation("Reader").
+		Where("book.id = ?", &book1.ID).
+		Select()
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("%+v \n", user)
+	fmt.Printf("%+v \n", users)
+	fmt.Printf("%+v \n", book)
+
+}
+
+func (c *PgClient) CreateTable() error {
+	models := []interface{}{
+		(*User)(nil),
+		(*Book)(nil),
+	}
+
+	for _, model := range models {
+		err := c.db.Model(model).CreateTable(&orm.CreateTableOptions{
+			Temp: true,
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

pgdb/pg-db.go

@@ -0,0 +1,35 @@
+package pgdb
+
+import (
+	"fmt"
+	"github.com/go-pg/pg/v10"
+	"sync"
+)
+
+var (
+	instance *pg.DB
+	once     sync.Once
+)
+
+func NewPgDB(pgOptions *pg.Options) *pg.DB {
+	once.Do(func() {
+		instance = Connect(pgOptions)
+	})
+
+	return instance
+}
+
+func Connect(pgOptions *pg.Options) *pg.DB {
+	db := pg.Connect(pgOptions)
+
+	var n int
+	_, err := db.QueryOne(pg.Scan(&n), "SELECT 1")
+	if err != nil {
+		fmt.Errorf("Connection error %+v\n", err)
+		panic(err)
+	}
+
+	fmt.Println("Successfully connected to ->", db.Options().Addr)
+
+	return db
+}