How do I say if($variable!=0) in OO PDO?

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Hi,

Ive recently been learning about OOP and PDO and think its really great but Im having a problem trying to convert some code from procedural programming to OOP.

I have some code to log in that checks that the query I run (using prepared statement) isnt empty, and the results of the query is stored in a variable.

PHP

$username = $_REQUEST['username'];
$password = $_REQUEST['password'];


$db = Database::getConnection();

if ($username&&$password)
{

$sqlQuery = "SELECT * FROM users WHERE username=:username";

$loginUser = $db->prepare($sqlQuery);

$loginUser->execute(array(':username' => $username));

if ($loginUser!=0)
{
//Do a while statement and store username, password, activated into variables
} else {
echo "User Doesnt Exist!";
}
}

The Problem is, is that I keep getting an error on the line "if ($loginUser!=0)" and I think its because there may be another method in OOP to check the SQL isnt empty.

Note: the Error I get is: "Notice: Object of class PDOStatement could not be converted to int...".

Many thanks for any help.

Posted 1-Dec-14 3:42am

jba1991

Updated 1-Dec-14 3:43am

v2

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Sergey Alexandrovich Kryukov · Answer 1 · 2014-12-01T04:46:00

Solution 1

Why some non-numeric object could be 0? From your code sample, it is apparent that $loginUser is an instance of some class (it has execute method, for example). So, you need this:
http://php.net/manual/en/function.is-null.php[^].

Note that the change in the if statement would not make your code correct. You are thinking about a check which is would be too late. For example, you are trying to call $loginUser->execute before the check, but in case where $loginUser is null, you would be dereferencing null object, which would throw the exception.

—SA

Posted 1-Dec-14 4:46am

Sergey Alexandrovich Kryukov

Comments

jba1991 1-Dec-14 11:23am

Would it work if I do "if(empty($loginUser))" and in the else statement execute the code to log in?

Sergey Alexandrovich Kryukov 1-Dec-14 11:26am

Why not? But it would work only if $loginUser is not null, and would be useful if an empty object may appear in your case. Empty objects are not null.
—SA

jba1991 1-Dec-14 11:36am

I just looked for the difference between empty and null, using empty will not work for me in this case i dont think.

What if I used "if($loginUser === NULL)"?

Sergey Alexandrovich Kryukov 1-Dec-14 14:02pm

Is it a kind of another question? The whole concept of "difference between empty and null" is nonsense. What is "difference"?

I told you how to do the check correctly; what's the problems with it?
=== is the "identity" operator; you can read about it.

—SA