Cannot return database object.

Question

This is my code for working with postgres database.

package main

import (
    "database/sql"
    _ "github.com/lib/pq"
    "fmt"
    "log"
)

//Details required for connection
const (
    HOST     = "HOSTNAME"
    USER     = "USER"
    PASSWORD = "PASSWORD"
    DATABASE = "DB"
)

func Create() (*sql.DB) {

    dbinfo := fmt.Sprintf("host=%s user=%s password=%s dbname=%s", HOST, USER, PASSWORD, DATABASE)
    db,err  := sql.Open("postgres", dbinfo)
    defer db.Close()

    if (err != nil) {
        log.Fatal(err)
    }

    err = db.Ping()

    if err != nil {
      log.Fatal(err)
    }

    return db
}


func main() {
    db := Create()
    querStmt, err := db.Prepare("select count(*) from table")

    if err != nil {
        fmt.Printf("Cannot prepare query\n")
        log.Fatal(err)
    }
    res, err := querStmt.Exec()
    if err != nil {
        fmt.Printf("Cannot execute query\n")
        log.Fatal(err)
    }

    fmt.Printf("%v\n", res)
}

When running this code i am getting this error

Cannot prepare query
2016/03/09 16:57:23 sql: database is closed

If i run query from Create() then it works perfectly but doing same on db object returned by Create() inside main() is not working. Thanks for help.

Ainar-G · Accepted Answer · 2016-03-09 16:32:56Z

3

Your database is closed the moment you return from Create because your defer is inside it and not inside main. Move the defer to main and it should work as intended.

answered Mar 9, 2016 at 16:32

Ainar-G

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1 Comment

shivams Over a year ago

Thanks. It was a go noob mistake :P

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