small php object oriented problem [duplicate]

Question

i having problem understanding what is wrong with my inheritance. I just can not call most of the function of the parent. below is the function i am stuck.

class MySQLi_DB  extends mysqli {
    private static $_instance = null;
    private function __construct($db="test",$host="localhost", $user="root", $pass="") 
    {

        parent::__construct($host, $user, $pass, $db);
        if (mysqli_connect_error()) {
            die('Connect Error (' . mysqli_connect_errno() . ') '
                    . mysqli_connect_error());
        }
    }
 static public function getDB()
    {
        if(self::$_instance == null)
        {
            self::$_instance = new MySQLi_DB();
        }
        return self::$_instance;

    }


public function insert($table,$data)
        {
           $sql = $this->getQuery($table,$data);
           print $sql;
        }

        public function getQuery($table, $inserts) 
        {
            $lambda = function($value){
                return $this->real_escape_string($value);
            };

            $values = array_map($lambda,$inserts);
            $keys = array_keys($inserts);

            return 'INSERT INTO `'.$table.'` (`'.implode('`,`', $keys).'`) VALUES (\''.implode('\',\'', $values).'\')';
        }

I am having problem calling real_escape_string() function . i have tried using $this->real_escape_string() but i just have to see this error

Fatal error: Using $this when not in object context in D:\wamp\www\Driver\MySQLi_DB.php on line 49

ok may be that could be limitation of lambda function but i have tried it other way by declaring a callback for array_map that also doesn't allow me to call real_escape_string.

i am calling the function as below.

require_once 'MySQLi_DB.php';
        $db = MySQLi_DB::getDB();

        $insert_data = array("cmsId"=>444,"pageName"=>"New Insert");
        $db->insert("cms",$insert_data);

Please point out where i am doing wrong and what could be the best way to do it. thanks

where is the real_escape_string() function?

user557846
– user557846

2011-06-07 05:14:59 +00:00
Commented Jun 7, 2011 at 5:14 — user557846
– user557846, Commented Jun 7, 2011 at 5:14
Can you post line 49 of MySQLi_DB.php if possible?

Babiker
– Babiker

2011-06-07 05:17:21 +00:00
Commented Jun 7, 2011 at 5:17 — Babiker
– Babiker, Commented Jun 7, 2011 at 5:17
thats is the line in lambda function

Khurram Ijaz
– Khurram Ijaz

2011-06-07 05:20:34 +00:00
Commented Jun 7, 2011 at 5:20 — Khurram Ijaz
– Khurram Ijaz, Commented Jun 7, 2011 at 5:20

J.C. Inacio · Accepted Answer · 2011-06-07 05:20:35Z

3

$lambda = function($value){
    return $this->real_escape_string($value);
};

On your 'lambda' function the context is not your object, so $this is not available.

As an alternative, you could use, for example:

$values = array_map('mysql_real_escape_string', $inserts)

or even try:

$values = array_map( array($this, 'real_escape_string'), $inserts)

this is untested but *should* work...

answered Jun 7, 2011 at 5:20

J.C. Inacio

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2 Comments

Khurram Ijaz Over a year ago

you rock maan. it is working amazing...can you please teach me what does this line of your means (array ( $this, 'real_escape_string') ?

J.C. Inacio Over a year ago

A callback (what is passed to array_map) can be either: a function, a function name, an array of (object, function), or array of (static class name, static function name)

Eineki · Accepted Answer · 2011-06-07 06:59:19Z

2

You can't use the $this keyword into a lamba function as the scope of the function does not extend to the object whose method contains the lambda

Try a different approach:

 public function getQuery($table, $inserts) 
 {
      $values = array_map(array($this, 'real_escape_string'),$inserts);
      $keys = array_keys($inserts);

      return sprintf('INSERT INTO %s (`%s`) VALUES ("%s")',
           $table,
           implode('`,`', $keys),
           implode('","', $values)
      );
    }

Addendum

If real_escape_string is not a method of your object but the standard msqli method you should change the line

 $values = array_map(array($this, 'real_escape_string'),$inserts);

to

 $values = array_map(array(self::$_instance, 'real_escape_string'),$inserts);

to call the method real_escape string.

The array array(self::$_instance, 'real_escape_string') is a callback array and it is used when you want to call an object method.

The php manual states

A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1

and self::$_instance is the mysqli instance you want to call

edited Jun 7, 2011 at 6:59

answered Jun 7, 2011 at 5:15

Eineki

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3 Comments

Khurram Ijaz Over a year ago

can you please tell me how else i can use the real_escape_string of mysqli.

Eineki Over a year ago

@g-molvi: Edited the answer to respond to your comment

Khurram Ijaz Over a year ago

Thanks Eineki, that is the real solution

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