Go expected identifier on left side of :=syntax - go

Question

Hello I am trying to make a connection to postgres using go, but I have the following error:
on this line :
conn.pool, err := sql.Open("postgres", uri)
err:
expected identifier on left side of :=syntax
I'm new to go and I don't know why and how to resolve this error, if someone can help me where I'm going wrong.
package database
import (
"database/sql"
"fmt"
"log"
"os"
"strconv"
)
type Db struct {
pool *sql.DB
}
type Connection interface {
Close()
DB() *sql.DB
}
func NewPostgreSQLsql() (Connection, error) {
var conn Db
uri := getURI()
conn.pool, err := sql.Open("postgres", uri)
if err != nil {
log.Fatal(err.Error())
return nil, err
}
if err := conn.Ping(); err != nil {
log.Fatal(err.Error())
return nil, err
}
return &conn, nil
}
func (c *db) DB() *sql.DB {
return c.pool
}
func (c *Db) Close() {
c.pool.Close()
}
func getURI() string {
dbPort, err := strconv.Atoi(os.Getenv("DB_PORT"))
if err != nil {
log.Println("error on load db port from env:", err.Error())
dbPort = 5432
}
return fmt.Sprintf(os.Getenv("DB_HOST"),
dbPort,
os.Getenv("DB_USER"),
os.Getenv("DB_NAME"),
os.Getenv("DB_PASSWORD"))
}

Answer 1

you cannot directly initialize and assign to conn.pool with :=
and you should initialize conn object
Try this
conn := Db{}
uri := getURI()
pool, err := sql.Open("postgres", uri)
conn.pool = pool
or
uri := getURI()
pool, err := sql.Open("postgres", uri)
conn := Db{pool}