PDO - Fatal error: Call to a member function prepare() on null - php

Question

I searched similar issues here but could not fix my problem.
I'm trying to add a search function to my website, but for some reason the search results are not displayed. In my error_log I get this error:
PHP Fatal error: Call to a member function prepare() on null in /home/..../search.php on line 9
which is this line:
$query = $pdo->prepare("SELECT * FROM subs WHERE sub_title LIKE '%$search%' LIMIT 0, 10");
Here is my search.php code:
<?php
require_once('includes/config.php');
include("includes/header.php");
// Search from MySQL database table
$search = $_POST['search'];
$query = $pdo->prepare("SELECT * FROM subs WHERE sub_title LIKE '%$search%' LIMIT 0, 10");
$query->bindValue(1, "%$search%", PDO::PARAM_STR);
$query->execute();
// Display search result
if(!$query->rowCount() == 0) {
echo "Search found:<br>";
echo "<table>";
echo "<tr><td>Title</td><td>Category></td><td>Language</td><td>Time</td><td>Download</td></tr>";
while($results = $query->fetch()) {
echo "<tr><td>";
echo $results['sub_title'];
echo "</td><td>";
echo $results['category'];
echo "</td><td>";
echo $results['sub_lang'];
echo "</td><td>";
echo $results['timestamp'];
echo "</td><td>";
echo $results['sub_data'];
echo "</td></tr>";
}
echo "</table>";
} else {
echo "Nothing found";
}
?>
Here is my config.php
<?php
$username = '------';
$password = '------';
try {
$conn = new PDO('mysql:host=localhost;dbname=-----', $username, $password, array(
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
));
}
catch(PDOException $e) {
echo "Failed to connect to database!" . "<br><br>";
echo $e->getMessage();
}
?>
and here is my search form which is in the header.php
<form class="form-inline" action="search.php" method="POST">
<input class="form-control" name="search" id="search" type="text" placeholder="Search">
</form>

Answer 1

you're using: $query = $pdo->prepare
It should be:
$query = $conn->prepare()
Because I am a lazy coder I made a new class to save a bit of time:
class DBCommon
{
private $conn;
/** #var Common */
public $common;
public function __construct()
{
$database = new Database();
$db = $database->dbConnection();
$this->conn = $db;
}
public function runQuery($sql)
{
$stmt = $this->conn->prepare($sql);
return $stmt;
}
}