Creating an array/slice to store DB Query results in Golang
Go has a built-in append
function for exactly this purpose. It takes a slice and one or more elements and appends those elements to the slice, returning the new slice. Additionally, the zero value of a slice (nil
) is a slice of length zero, so if you append to a nil slice, it will work. Thus, you can do:
type User struct {
Id int
Title string
}
func Find_users(db *sql.DB) {
// Query the DB
rows, err := db.Query(`SELECT u.id, u.title FROM users u;`)
if err != nil {
log.Fatal(err)
}
defer rows.Close()
var users []User
for rows.Next() {
err := rows.Scan(&id, &title)
if err != nil {
log.Fatal(err)
}
log.Println(id, title)
users = append(users, User{Id: id, Title: title})
}
if err := rows.Err(); err != nil {
log.Fatal(err)
}
// ...
}
User appending to a slice:
type DeviceInfo struct {
DeviceName string
DeviceID string
DeviceUsername string
Token string
}
func QueryMultiple(db *sql.DB){
var device DeviceInfo
sqlStatement := `SELECT "deviceName", "deviceID", "deviceUsername",
token FROM devices LIMIT 10`
rows, err := db.Query(sqlStatement)
if err != nil {
panic(err)
}
defer rows.Close()
var deviceSlice []DeviceInfo
for rows.Next(){
rows.Scan(&device.DeviceID, &device.DeviceUsername, &device.Token,
&device.DeviceName)
deviceSlice = append(deviceSlice, device)
}
fmt.Println(deviceSlice)
}