Golang : How to check if a connection to database is still alive ?

Problem :

How to check if a connection to database is still alive ?

Solution :

Use DB.Ping function. For example :

 package main

 import (
 "database/sql"
 "fmt"

 // without the underscore _, you will get imported but not
 // used error message
 _ "github.com/go-sql-driver/mysql"
 "os"
 )

 func main() {

 // connect to our database server with data source name
 // data source name configuration has the following parameters :
 // [username[:password]@][protocol[(address)]]/dbname[?param1=value1&...&paramN=valueN]

 // example config :
 // user:password@tcp(127.0.0.1:3306)/database

 conn, err := sql.Open("mysql", "db_username:db_password@protocol(address:port_num)/database_name")
 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 err = conn.Ping()

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // if no error. Ping is successful
 fmt.Println("Ping to database successful, connection is still alive")

 conn.Close()

 // this part should fail

 err = conn.Ping()

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // if no error. Ping is successful
 fmt.Println("Ping to database successful, connection is still alive")
 }

Output :

Ping to database successful, connection is still alive

sql: database is closed

exit status 1

References :

http://golang.org/pkg/database/sql/#DB.Ping