PHP from Java script

tsbalaban

I have an input form with text and a save button to go to a data base thru PDO. I want to lock tables for whole time of inputing thru saving to data base before page refreshes.

Details:
I tried onclick with "<?php ?>" and "<script src=". Do not work. Only Java script function works. My data base save function is PHP. How do I call PHP from Java script? I may need to save PDO handle. Will not work with session
save method.

Krik

You can not call PHP form javascript. PHP is a server side script it only runs when there is an http request (page load). Javascript is a client side script (browser), so as no PHP is passed to the browser javascript can not run the PHP scripts. And even if PHP was passed to the browser most computers have no way of knowing how to process PHP.

Now if you use AJAX javascript can receive the out put from some PHP, but AJAX is an function for letting javascript send an http request, without the user seeing a page load.

anoopmail

lock the value using the seeion id and release lock when a post request come from the same session id. Also need to release lock when a time out occures because of long time inactivity.

tsbalaban

I don't ubderstand about locks in last post. I tried AJAX that is the way to go. I initially use a data base with PDO. I cannot pass a PDO handle that is an Object thru AJAX. PHP Object is not equal to Java script Object.

Details:
I tried $_SESSION, serialize, and pack. Error is "can not convert Object to String". If I reset the handle, I lose my lock tables and do not have a continuous session. Someone else could corrupt my database values. I use Tw-Sack AJAX, perhaps jQuery would be better.

Thank you for any assistamce.

Krik

You shouldn't need to pass the handle through AJAX. Have the handle in the PHP file that AJAX requests. If you have to vary the handle have AJAX pass a value that PHP can use to determine which handle to use. Heck you could just pass the handles name and then turn it into a variable.

$$_POST['handle'];

If AJAX had the "handle" set to "mypdo" the variable would be "$mypdo" and if the "$mypdo" object is defined in your PHP you can now use it for whatever you need.

tsbalaban

I do not understand the last post.
$$POST is retrieval from the PHP server side of Ajax. I tried variable variable $$. Pleae post a simple example for how to pass PDO handle after initial creation. $POST will not work befor AJax call.

Thank you for any assistance.

johanafm

Once again, you do NOT pass the handle around between client and server. If the client does need to specify which database connection to use, but otherwise uses the exact same tables and queries, you could do it like this (which is according to the previous post), and in my opinion only suitable if you for some reason connect to several databases on every request

$db1 = new PDO(...);
$db2 = new PDO(...);

if (!empty($_POST)) {
	# handle is not specified. use default
	if (!isset($_POST['handle'])) {
		$handle = $db1;
	}
	# specified handle does not exist. use default. (or perhaps log error and exit)
	# e.g. $_POST['handle'] == 'db3' => $db3 is not set...
	elseif (!isset($$_POST['handle']) {
		$handle = $db1;
	}
	else {
		# if $_POST['handle'] == 'db1', then $handle = $db1;
		# if $_POST['handle'] == 'db2', then $handle = $db2;
		$handle = $$_POST['handle'];
	}

$stmt = $handle->query(...);
}

Otherwise you might just as well do it like this

$db1 = new PDO(...);
$db2 = new PDO(...);

if (!empty($_POST)) {
	# handle is not specified. use default
	if (!isset($_POST['handle'])) {
		$handle = $db1;
	}
	# specified handle does not exist. use default. (or perhaps log error and exit)
	# e.g. $_POST['handle'] == 'db3' => $db3 is not set...
	elseif (!isset($$_POST['handle']) {
		$handle = $db1;
	}
	else {
		# if $_POST['handle'] == 'db1', then $handle = $db1;
		# if $_POST['handle'] == 'db2', then $handle = $db2;
		$handle = $$_POST['handle'];
	}

$stmt = $handle->query(...);
}