I am trying to establish a PDO connection using the try block and then printing a success message after the connection gets established. My code is as follows:
index.php :
<?php
require_once './vendor/autoload.php';
$con = new \app\db\Connect();
if ($con)
{
echo 'connection successful.';
}
connect.php
<?php
namespace app\db;
class Connect
{
public function __construct()
{
// set the connection variables
$host = 'localhost';
$dbname = 'pdoposts';
$username = 'root';
$password = 'root';
// create the DSN
$dsn = 'mysql:host=' . $host . ';dbname=' .$dbname;
// create PDO connection
try {
static $con;
$con = new PDO($dsn, $username, $password);
} catch(Exception $e) {
echo $e->getMessage();
}
return $con;
}
}
My problem is that there is no way for me to use the $concreated in the try - catch command in the index.php file. I am very sorry if this question seems very basic and elemental one, but please help me understand how it can work. Thank you very much in advance.
Accoring to the answer below:
The solution here on stackoverflow
I just added the backslash right before PDO and made it to be \PDO and it is now working properly. The link below can help understanding PHP Callbacks and how they work better:
Using namespaces: fallback to global function/constant
I should have kept in mind the namespace from which I wanted to use PDO from. In this case, using a \ would tell php to use PDO from the Global Namespace and not from the namespace from which the code runs in (app\db).
Related
I'm trying to include a variable from a different file into my main php file but I keep getting Undefined variable.
accounts.php
# GUEST CREDENTIALS
$host = 'localhost';
$guestAccount = 'oncofinder';
$guestPassword = 'xxxxxx';
$database = 'oncofinder';
#LOGGER CREDENTIALS
$loggerAccount = 'logger';
$loggerPassword = 'xxxxx';
connections.php
function guestConnection() {
try {
require 'accounts.php';
$conn = new PDO("pgsql:host=$host;dbname=$database", $guestAccount, $guestPassword);
} catch (PDOException $e) {
echo "Error : " . $e->getMessage() . "<br/>";
die();
}
$conn->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
I tried to put my require in and out of my function but nothing works. I really thought this was straightfoward but I can't find an obvious solution.
Is there any thing I'm doing wrong? Isn't this the procedure?
Regards
I think you have variables defined in global scope but you try to use it in local scope.
To confirm naming scope issue try to:
require 'accounts.php';
function guestConnection() {
global $host, $database, $guestAccount, $guestPassword;
try {
$conn = new PDO("pgsql:host=$host;dbname=$database", $guestAccount, $guestPassword);
...
This should work if your guestConnection() is in global scope not under any namespace or class.
or do move require out of try to get errors if any (file does not exist?):
function guestConnection() {
require('accounts.php');
try {
$conn = new PDO("pgsql:host=$host;dbname=$database", $guestAccount, $guestPassword);
...
I had a similar problem on my CentOS server. Try using the full absolute path (server conf might not be configured to allow calling of same-level files this way):
require_once $_SERVER['DOCUMENT_ROOT']. '/path/to/accounts.php';
Note:
you can use require and it should still work. I just think require_once is safer (in terms of not accidentally duping code).
I am trying to create a PDO object in a class and then use it in another file. The PDO Object gets created (as far as I understand) but I can not use it in the other file and I view these outputs:
PDO Object ( )
connection successful.
Fatal error: Uncaught Error: Call to undefined method
app\db\Connect::query() in /var/www/html/pdoTest/index.php:25 Stack
trace: #0 {main} thrown in /var/www/html/pdoTest/index.php on line 25
My code is as following:
index.php
<?php
ini_set('display_errors', '1');
require_once './vendor/autoload.php';
$con = new \app\db\Connect();
if (!$con)
{
echo 'no PDO object available.';
}else{
echo 'connection successful.' . '<br>';
}
connect.php
<?php
namespace app\db;
use PDO;
class Connect
{
public function __construct()
{
// set the connection variables
$host = 'localhost';
$dbname = 'pdoposts';
$username = 'root';
$password = 'root';
// create the DSN
$dsn = 'mysql:host=' . $host . ';dbname=' .$dbname;
// create PDO connection
try {
$con = new PDO($dsn, $username, $password);
print_r($con);
echo '<br>';
} catch(Exception $e) {
echo $e->getMessage();
}
return $con;
}
}
I have searched all over stackoverflow and other parts of internet but as it seems I am out of luck understanding what my problem is in using the created PDO object. Would you please help me understand it?
There is something, as a newbie, that a I want to understand about About database connections.
I am starting off from a tutorial on PHP which has this structure:
Connect.php:
<?php
$username = "dbusername";
$password = "dbpassword";
$host = "localhost";
$dbname = "dbname";
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
try
{
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex)
{
die("Failed to connect to the database: " . $ex->getMessage());
}
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
header('Content-Type: text/html; charset=utf-8');
session_start();
?>
Login.php:
<?php
require("connect.php");
// some code not important for this question,
//that handles login with a session…
?>
various_file_in_the_login_system.php:
<?php
require("connect.php");
// some code that checks if user is logged in with session_ …
// some code that does need the database connection to work
?>
All other files also contain that require("connect.php"); line. It works, but I just don’t know what these connection request to the server – I may not be using the right vocabulary -- end up doing to the server. They are superfluous if the connection is not timed out, are they not?
I found a post which talked about doing a singleton for PDO, and a post which makes me feel like never using persistent connections in my life.
Does this design causes excessive connection churning?
Perhaps servers can handle very many request for connection per second, perhaps a server has its own internal persistent connection mode, or implements connection pooling…
Or the PDO object handle the problem of asking connection too often for no reason…
PDO + Singleton : Why using it?
What are the disadvantages of using persistent connection in PDO
This is what I can recommend for your database connection:
Make a class for the connection:
class Database{
private static $link = null ;
public static function getConnection ( ) {
if (self :: $link) {
return self :: $link;
}
$dsn = "mysql:dbname=social_network;host=localhost";
$user = "user";
$password = "pass";
self :: $link = new PDO($dsn, $user, $password);
return self :: $link;
}
}
Then you can get the connection like this:
Database::getConnection();
The Singleton Pattern is hard to scale - However, I think it will probably be fine for your needs. It takes a lot of load off your database.
I don't think you will be able to avoid the multiple includes.
There is a php.ini setting for prepending a file to every script -> http://www.php.net/manual/en/ini.core.php#ini.auto-prepend-file
How about you change to
require_once('connect.php');
in all locations?
Also you should probably remove session_start() and HTTP header logic from a section of code that has to do with establishing a DB connection. This simply does not make sense there.
This question already has an answer here:
PHP: mysql_connect not returning FALSE
(1 answer)
Closed 8 years ago.
I'm very new to OOP and am trying to learn it. So please excuse my noobness. I'm trying to connect to mysql and to test whether the connection is successful or not, I'm using if-else conditions.
Surprisingly, the mysql_connect is always returning true even on passing wrong login credentials. Now I'm trying to figure out why it does and after spending about 20 minutes, I gave up. Hence, I came here to seek the help of the community. Here is my code:
class test
{
private $host = 'localhost';
private $username = 'root2'; // using wrong username on purpose
private $password = '';
private $db = 'dummy';
private $myConn;
public function __construct()
{
$conn = mysql_connect($this->host, $this->username, $this->password);
if(!$conn)
{
die('Connection failed'); // this doesn't execute
}
else
{
$this->myConn = $conn;
$dbhandle = mysql_select_db($this->db, $this->myConn);
if(! $dbhandle)
{
die('Connection successful, but database not found'); // but this gets printed instead
}
}
}
}
$test = new test();
Please don't use the mysql_* functions, there are many, many reasons why - which are well documented online. They are also deprecated and due to be removed.
You'd be much better off using PDO!
Also I'd strongly advise abstracting this database code into a dedicated database class, which can be injected where necessary.
On-topic:
That code snippet seems to work for me, have you tried var_dumping $conn? Does that user have correct rights?
I also hope that you don't have a production server which allows root login without a password!
Ignoring the fact that you're using mysql_* functions rather than mysqli or pdo functions, you should utilise exceptions in OOP code rather than die(). Other than that, I can't replicate your problem - it may be that your mysql server is set up to accept passwordless logins.
class test
{
private $host = 'localhost';
private $username = 'root2'; // using wrong username on purpose
private $password = '';
private $db = 'dummy';
private $myConn;
public function __construct()
{
// returns false on failure
$conn = mysql_connect($this->host, $this->username, $this->password);
if(!$conn)
{
throw new RuntimeException('Connection failed'); // this doesn't execute
}
else
{
$this->myConn = $conn;
$dbhandle = mysql_select_db($this->db, $this->myConn);
if (!$dbhandle)
{
throw new RuntimeException('Connection successful, but database not found'); // but this gets printed instead
}
}
}
}
try {
$test = new test();
} catch (RuntimeException $ex) {
die($ex->getMessage());
}
I'm working on my own SignUp class but it seems I have a problem with the PDO calls
The browser returns this to me:
Fatal error: Call to a member function query() on a non-object
I have my database configuration in a file included then on the main page. It's as follows:
<?
$dsn = 'mysql:dbname=magazin-online;host=localhost;';
$username = 'root';
$password = '';
try{
$pdo = new PDO($dsn, $username, $password);
}catch(PDOException $e){
echo 'Connection failed!: '.$e->getMessage();
}
An the line in the SignUp class causing the error is this:
$pdo->query("insert into ... () ... values ());
Now, I don't make any db connection in my SignUp class because I already included the file resposible for it.
How can I get rid of that error?
try using exec instead of query:
$pdo->exec("insert into ... () ... values ());
You are catching the exception generated by the new PDO, and then continue execution.
By doing it this way, you have to check that the class exists, so change:
if( $pdo)
$pdo->query("insert into ... () ... values ());
But .. a better way is not to continue execution after a critical error like this.
So better change the connection like this:
$dsn = 'mysql:dbname=magazin-online;host=localhost;';
$username = 'root';
$password = '';
try{
$pdo = new PDO($dsn, $username, $password);
}catch(PDOException $e){
echo 'Connection failed!: '.$e->getMessage();
die;
}
If I understand correctly, $pdo is a global variable. If you are calling $pdo->query inside a function, you either have to pass the $pdo connection as a parameter or declare it as global
global $pdo;
in the beginning of the member function.