PHP PDO Class connection

Question

Hello so currently I've downloaded a PHP PDO class and this what it looks like:

class db extends PDO {
    private $error;
    private $sql;
    private $bind;
    private $errorCallbackFunction;
    private $errorMsgFormat;

    public function __construct($dsn, $user="", $passwd="") {
        $options = array(
            PDO::ATTR_PERSISTENT => true, 
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        );

        try {
            parent::__construct($dsn, $user, $passwd, $options);
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
        }
    }

    private function debug() {
        if(!empty($this->errorCallbackFunction)) {
            $error = array("Error" => $this->error);
            if(!empty($this->sql))
                $error["SQL Statement"] = $this->sql;
            if(!empty($this->bind))
                $error["Bind Parameters"] = trim(print_r($this->bind, true));

            $backtrace = debug_backtrace();
            if(!empty($backtrace)) {
                foreach($backtrace as $info) {
                    if($info["file"] != __FILE__)
                        $error["Backtrace"] = $info["file"] . " at line " . $info["line"];  
                }       
            }

            $msg = "";
            if($this->errorMsgFormat == "html") {
                if(!empty($error["Bind Parameters"]))
                    $error["Bind Parameters"] = "<pre>" . $error["Bind Parameters"] . "</pre>";
                $css = trim(file_get_contents(dirname(__FILE__) . "/error.css"));
                $msg .= '<style type="text/css">' . "\n" . $css . "\n</style>";
                $msg .= "\n" . '<div class="db-error">' . "\n\t<h3>SQL Error</h3>";
                foreach($error as $key => $val)
                    $msg .= "\n\t<label>" . $key . ":</label>" . $val;
                $msg .= "\n\t</div>\n</div>";
            }
            elseif($this->errorMsgFormat == "text") {
                $msg .= "SQL Error\n" . str_repeat("-", 50);
                foreach($error as $key => $val)
                    $msg .= "\n\n$key:\n$val";
            }

            $func = $this->errorCallbackFunction;
            $func($msg);
        }
    }

    public function delete($table, $where, $bind="") {
        $sql = "DELETE FROM " . $table . " WHERE " . $where . ";";
        $this->run($sql, $bind);
    }

    private function filter($table, $info) {
        $driver = $this->getAttribute(PDO::ATTR_DRIVER_NAME);
        if($driver == 'sqlite') {
            $sql = "PRAGMA table_info('" . $table . "');";
            $key = "name";
        }
        elseif($driver == 'mysql') {
            $sql = "DESCRIBE " . $table . ";";
            $key = "Field";
        }
        else {  
            $sql = "SELECT column_name FROM information_schema.columns WHERE table_name = '" . $table . "';";
            $key = "column_name";
        }   

        if(false !== ($list = $this->run($sql))) {
            $fields = array();
            foreach($list as $record)
                $fields[] = $record[$key];
            return array_values(array_intersect($fields, array_keys($info)));
        }
        return array();
    }

    private function cleanup($bind) {
        if(!is_array($bind)) {
            if(!empty($bind))
                $bind = array($bind);
            else
                $bind = array();
        }
        return $bind;
    }

    public function insert($table, $info) {
        $fields = $this->filter($table, $info);
        $sql = "INSERT INTO " . $table . " (" . implode($fields, ", ") . ") VALUES (:" . implode($fields, ", :") . ");";
        $bind = array();
        foreach($fields as $field)
            $bind[":$field"] = $info[$field];
        return $this->run($sql, $bind);
    }

    public function run($sql, $bind="") {
        $this->sql = trim($sql);
        $this->bind = $this->cleanup($bind);
        $this->error = "";

        try {
            $pdostmt = $this->prepare($this->sql);
            if($pdostmt->execute($this->bind) !== false) {
                if(preg_match("/^(" . implode("|", array("select", "describe", "pragma")) . ") /i", $this->sql))
                    return $pdostmt->fetchAll(PDO::FETCH_ASSOC);
                elseif(preg_match("/^(" . implode("|", array("delete", "insert", "update")) . ") /i", $this->sql))
                    return $pdostmt->rowCount();
            }   
        } catch (PDOException $e) {
            $this->error = $e->getMessage();    
            $this->debug();
            return false;
        }
    }

    public function select($table, $where="", $bind="", $fields="*") {
        $sql = "SELECT " . $fields . " FROM " . $table;
        if(!empty($where))
            $sql .= " WHERE " . $where;
        $sql .= ";";
        return $this->run($sql, $bind);
    }

    public function setErrorCallbackFunction($errorCallbackFunction, $errorMsgFormat="html") {
        //Variable functions for won't work with language constructs such as echo and print, so these are replaced with print_r.
        if(in_array(strtolower($errorCallbackFunction), array("echo", "print")))
            $errorCallbackFunction = "print_r";

        if(function_exists($errorCallbackFunction)) {
            $this->errorCallbackFunction = $errorCallbackFunction;  
            if(!in_array(strtolower($errorMsgFormat), array("html", "text")))
                $errorMsgFormat = "html";
            $this->errorMsgFormat = $errorMsgFormat;    
        }   
    }

    public function update($table, $info, $where, $bind="") {
        $fields = $this->filter($table, $info);
        $fieldSize = sizeof($fields);

        $sql = "UPDATE " . $table . " SET ";
        for($f = 0; $f < $fieldSize; ++$f) {
            if($f > 0)
                $sql .= ", ";
            $sql .= $fields[$f] . " = :update_" . $fields[$f]; 
        }
        $sql .= " WHERE " . $where . ";";

        $bind = $this->cleanup($bind);
        foreach($fields as $field)
            $bind[":update_$field"] = $info[$field];

        return $this->run($sql, $bind);
    }
}   

And every time I use it I need to include it in a page like include("class.db.php"); and also provide my data source name, username and password like this $db = new db("mysql:host=localhost;dbname=db_information", "root", "");. What I wanted to do is instead of always providing that line, I want to include it in my class. What I do is put that line in the last part of the class but it looks dirty. How can I include it in my class?

Answer 1

You are not supposed to add this to your class. If you really want to connect automatically without always entering your credentials, the best you should do would be to create a configuration file and include it at the beginning of each page requiring a connection.

Answer 2

Change your constructor into this:

public function __construct($dsn='', $user='', $passwd='') {
    $options = array(
        PDO::ATTR_PERSISTENT => true, 
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    );

    if (empty($dsn)) {
        $dsn = 'mysql:host=localhost;dbname=db_information';
    }

    if (empty($user)) {
        $user = 'root';
    }

    try {
        parent::__construct($dsn, $user, $passwd, $options);
    } catch (PDOException $e) {
        $this->error = $e->getMessage();
    }
}

This way you can still provide an other connection then this default one.