Trouble importing local package - go

Question

I've decided to try breaking my project into a MVC type view, so to start I wanted to put all my routing into a controller folder and I put my database connection into another folder titled db.
I can't figure out how to make the database connection work smoothly. Back when all of the files were in my package main I just called InitDb() in main and in all of my other files in the main package I had access to the db variable. Now that I made db it's down package and imported it, nothing is recognized.
I also don't know where to call InitDb() and defer db.Close() anymore since it's not all in main.
db/db.go
package database
import (
"fmt"
"database/sql"
)
var db *sql.DB
const (
dbhost = "localhost"
dbuser = "root"
dbpass = "password"
dbname = "user"
)
func InitDb() {
var err error
connectionString := fmt.Sprintf("%s:%s#/%s", dbuser, dbpass, dbname)
db, err = sql.Open("mysql", connectionString)
if err != nil {
panic(err)
}
err = db.Ping()
if err != nil {
panic(err)
}
fmt.Println("Successfully connected!")
}
controllers/index.go
package controllers
import (
"net/http"
"fmt"
"db"
"github.com/gorilla/mux"
)
func TestHandler(r *mux.Router)
r.HandleFunc("/index", test).Methods("GET")
}
func test(w http.ResponseWriter, r *http.Request) {
// database undefined
err := database.QueryRow("some sql statement")
CheckErr(err)
}
main.go
package main
import (
"net/http"
_ "github.com/go-sql-driver/mysql"
"github.com/gorilla/mux"
)
func main() {
r := mux.NewRouter()
controllers.TestHandler(r)
log.Fatal(http.ListenAndServe("localhost:8000", r))
}

Answer 1

While not required it is a good idea to have the package name be the same as the folder in which it lives, so either do:
db/db.go
package db
// ...
Or do:
database/db.go
package database
// ...
I would not recommend mixing the two.
You can have your database package export a Close function and have main call it when it's done.
database/db.go
package database
import (
"fmt"
"database/sql"
)
var db *sql.DB
func Close() {
db.Close()
}
// ...
main.go
package main
import "database"
func main() {
defer database.Close()
// ...
}
Or just don't close it in this case. When main exits the *sql.DB does not stay alive outside your program, it will not take up connection slots if the program is not running. Closing makes sense only if you're using multiple instances of *sql.DB and there is danger that they will start blocking while waiting for a connection. If you have only one that's shared by the whole program then you should be ok not calling defer close.