Accessing private variable in PHP ( PDO)

Question

I am using PDO in PHP ... I have the following problem.

The following code does not work.

class A {
 private $getUsersQuery = "SELECT * FROM users";      
 ...
 public function getUsers() {       
   $DBH = A::getDatabaseConnection();           
   try {
      $query = $DBH->prepare($this->getUsersQuery); 
      ...
   } catch(PDOException $e) {}
 }
}

But if I use the string it works.

$DBH->prepare("SELECT * FROM users");

Even if I use the echo outside the prepare() it works ...

echo $this->getUsersQuery;   // Outputs the sql string.

Can someone point out what the problem might be.

Update :

Error :

SQLSTATE[42000]: Syntax error or access violation: 1065 Query was empty

Thanks

Agreed it should work. What exactly do you mean by 'does not work'? Any error message? — Tchoupi, Nov 17 '12 at 22:31
The most important question here is: How does it NOT work? What error message to you get, etc.? — markus, Nov 17 '12 at 22:35
Well, I wouldn't say the code looks perfect but we really need to know what errors you get. — markus, Nov 17 '12 at 22:36
I get the following error SQLSTATE[42000]: Syntax error or access violation: 1065 Query was empty ... But echo $this->getUsersQuery; shows the query string.. — Fox, Nov 17 '12 at 22:38
try-catch blocks are just useful if you are doing something with the exception (i. e. output the error message to a file). if you are using it to hide error messages you will never know why your code not work. — iRaS, Nov 17 '12 at 22:39
@Dr.Molle I call getUsers() from another class like this $results = A::getUsers(); — Fox, Nov 17 '12 at 22:42
what kind of database handle do you get? may be the method prepare gets a reference (i. e.: public function prepare(&$query) {...}) and the reference is not accessible for the database handle class. — iRaS, Nov 17 '12 at 22:43
@iRaS I think the DB handle works fine coz ... $DBH->prepare("SELECT * FROM users"); does not give me any problem. — Fox, Nov 17 '12 at 22:45
so you call a non static method statically? the instance variable is not available in there. you have to create an instance of A: "$a = new A(); $a->getUsers();" i always tell my team members they should enable strict warnings for development environment just because you can see your errors. — iRaS, Nov 17 '12 at 22:45
How did this even pass parsing? If you a calling a non-static member function without an object? Something is very funky with this question. — Lightness Races in Orbit, Nov 17 '12 at 22:48
thats right. i just tried this (does i remember correctly?). you have to get a fatal error: Using $this when not in object context — iRaS, Nov 17 '12 at 22:51

score 4 · Accepted Answer · answered Nov 17 '12 at 22:45

4

As mentionned in your comment, you make a static call to a method that is not static.

Using $this in a method that is called like this makes no sense:

$results = A::getUsers();

Instanciate your class, and then call the method on the class object.

$a = new A();
$a->getUsers();

Or make your method and SQL query static.

answered Nov 17 '12 at 22:45

Tchoupi

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How did the original code even parse? – Lightness Races in Orbit Nov 17 '12 at 22:50
@LightnessRacesinOrbit It seems that the OP stated otherwise :P But I do understand your point. I know that somehow PHP doesn't seem to care when you statically call a non static method, and most of the times will throw a warning but execute the code anyway. So why did it work with an `echo` and not in a method parameter is a mystery to me. – Tchoupi Nov 17 '12 at 22:51
1

@MathieuImbert: [Holy heck](http://ideone.com/iXz0Nn). What a sorry state of affairs... – Lightness Races in Orbit Nov 17 '12 at 22:52
@LightnessRacesinOrbit Yes I've noticed that in production while cleaning the error logs. My guess is that a simple `echo` PHP will just *convert* the non static variable to a static one. But in the case of a parameter, it needs to get a reference of it and fails. – Tchoupi Nov 17 '12 at 22:55
1

@MathieuImbert even the call to $this when called statically should throw a fatal error. at least in my php version (5.3.10) – iRaS Nov 17 '12 at 22:56
1

@iRaS It seems that this issue was discussed before: http://stackoverflow.com/questions/2439036/does-static-method-in-php-have-any-difference-with-non-static-method – Tchoupi Nov 17 '12 at 22:59
@MathieuImbert alright, thanks - that was new to me. so it is an object of class A that is is calling A::getUsers(). very complicated to debug, uh? – iRaS Nov 17 '12 at 23:06

score 0 · Answer 2 · answered Nov 17 '12 at 22:45

0

Try

$a = new A();
$result = $a->getUsers();

The value of $getUsersQuery was probably not initialized when you called A::getUsers(). Static methods are called liked that.

answered Nov 17 '12 at 22:45

codingbiz

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Accessing private variable in PHP ( PDO)

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