Using function to create a connection

Question

I'm trying to create a connection using function in my other php file. So I can access it in every php file. How can I call the function inside my class from another php file. What is the proper way creating instance of my function will I put it in the top of my file or inside my class? I try to run my system but the connection won't load.

connection.php

<?php

DEFINE ('host', 'localhost');
DEFINE ('username', 'root');
DEFINE ('password', '');
DEFINE ('database', 'librarysystem');

function getConnection()
{
$myDB = mysqli_connect(host,username,password,database);

if (!$myDB)
{
    trigger_error ('Could not connect to MySQL: ' . mysqli_connect_error());
}
else
{
    return $myDB;
}
}                         
?>

Another file where I'm gonna call my function or method.

loginCRUD.php

<?php
error_reporting(0);

require_once ('../connection/connection.php');

$myConnection = getConnection();

class loginCRUD
{
public function readLogin($dbusername,$dbpassword)
{
    $statement = $myConnection->prepare("SELECT * FROM loginmodule WHERE loginUsername = ? AND loginPassword = ? LIMIT 1");
    $statement->bind_param("ss", $dbusername, $dbpassword);
    if($statement->execute())
    {
        $result = $statement->get_result();
        if($result->num_rows)
        {
            $row = $result->fetch_assoc();
            return $row;
        }
        else
        {
            return false;
        }
    }
    else
    {
        return false;
    }
}
}
(new loginCRUD)->readLogin($dbusername,$dbpassword);
?>

Shouldn't `$myDatabase` on the line where you define your statement just be `$myConnection`? — Dacaspex, May 10 '16 at 17:12
Pass `$myConnection` as an argument to a constructor for example. — u_mulder, May 10 '16 at 17:13
@gre_gor What the eye does not see, the developer does not have to fix _hehehhe_ So annoying I agree — RiggsFolly, May 10 '16 at 18:28

score 1 · Accepted Answer · answered May 10 '16 at 17:20

There can be at least two possible ways of passing $myConnection to your loginCRUD class.

First is to create $myConnection in a class itself:

class loginCRUD
{
    protected $dbCon;

    public function __construct() 
    {
       $this->dbCon = getConnection();
    }

    public function readLogin($dbusername,$dbpassword)
    {
        $statement = $this->dbCon->prepare("YOUR SQL")
        // other codes
    }
}

(new loginCRUD)->readLogin($dbusername,$dbpassword);

Second is to pass $myConnection as an argument to your class constructor:

class loginCRUD
{
    protected $dbCon;    

    public function __construct($myCon) 
    {
       $this->dbCon = $myCon;
    }

    public function readLogin($dbusername,$dbpassword)
    {
        $statement = $this->dbCon->prepare("YOUR SQL")
        // other codes

    }
}

$myConnection = getConnection();
(new loginCRUD($myConnection))->readLogin($dbusername,$dbpassword);

I prefer your first example! So glad you help :) – Francisunoxx May 10 '16 at 17:28 — Francisunoxx, May 10 '16 at 17:28

score 0 · Answer 2 · edited May 23 '17 at 12:16

The reason you are getting an error is due to your variable scope. In your loginCRUDclass you try to access a variable called myConnection, it fails to find it because the scope of the function is only that function. It doesn't know that you mean the global declared variable. A correct way of fixing this should be:

...
public function readLogin($dbusername,$dbpassword)
{
    global $myConnection;
    $statement = $myConnection->prepare("SELECT * FROM loginmodule WHERE loginUsername = ? AND loginPassword = ? LIMIT 1");
    $statement->bind_param("ss", $dbusername, $dbpassword);
    if($statement->execute())
    {
...

For reference: Accessing variables and methods outside of class definitions

Using function to create a connection

2 Answers2