[Resolved] Can you call a function from a form submit action?

printelectric

I am working on a page that updates a MySQL database. Everything has tested fine, and is working with the standard Dreamweaver behaviors (MM_insert, etc).

I would like to rewrite some of these behaviors as functions so that I can put multiple forms on a page (so that a user could do updates / deletes / inserts from the same place).

The problem with this is that the Dreamweaver behavior does all this with variable reassignment, which executes all code every time the page is loaded.

I'm just testing at the moment, so I've stripped this down to the bones just for the sake of readability. For a while $_POST variables were coming up as defined within my function, but only sporadically, and my redirects were sometimes working as advertised. Now, I'm really not getting anything.

What I would really like is to be able to call a function directly from a form, and return the URL from the function to the form action (which would then update data, or refresh, or redirect to an error page, or whatever).

Obviously there's something big that I'm missing here. Any help would be greatly appreciated.

<?php function test() {
	if(isset($_POST['email'])) {
	/* code will go here to parse variables and put together an SQL query */
		$url = "clientAdmin.php";
		return($url); 
	} else {
		$url = "error.php";
		return($url);
	}
}
$clientInsert = test(); 
?>


Call function the old school Dreamweaver way...<Br>
<form name="clientInsert" action="<?php echo $clientInsert; ?>" method="POST">
	Email <input type="text" name="email"><br>
	<input type="submit" value="add client">
</form>

<hr>

Call function without the variable reassignment shuffle...<br>
<form name="clientDelete" action="<?php test(); ?>" method="POST">
	Email <input type="text" name="email"><br>
	<input type="submit" value="delete client">
</form>

dalecosp

Hmm, interesting.

I'm not sure whether I'm groking your problem correctly. However, in the example, I can see that although you've got good ideas, the "big thing" that you're missing is that the test() function isn't printing anything to the browser, and therefore your HTML form will be coming to you without an action attribute...

So, you could have the function echo/print the URL, or you could actually do some logic in that PHP block and test the value returned, then echo it.

Also (and this is likely by your design, as you simplified the code), your function doesn't seem to indicate whether or not the SQL query was successful or not ....

I'm probably missing something here, too; but I thought I'd give it a shot ....

printelectric

Yeah. I've tried this about 50 different ways now. I think the real problem is that $_POST is undefined within my function, but I would really like some clarification on that.

I don't know if $_POST should be defined the instant that the user clicks "submit", or if it only becomes defined as something gets submitted to the server for processing.

In response to your comments, I've stripped out all of my SQL interaction, because that's all working fine. I basically am just trying to establish two things:

1) Can I call a function from a form in this way:
<form action="<?php return someFunction(); ?>">

2) Within said function, should I be able to access values from $_POST?

The goal of this, ultimately, would be to put together an SQL query within the function, update the database with the user supplied values, and conditionally send back a URL for the browser (that would be the return value of the function).

My reasons for this:
1) The Dreamweaver server behaviors all work through a chain of variable reassignments. As such, they execute every time a page loads if $_POST values are set.

2) This means that if you have two forms on a page, and click submit, the submission will execute ALL of the behaviors on the page, because the script will reload, and $_POST will be set.

3) If I can wrap all of these behaviors in a function, they will ONLY execute if explicitly called from the form action.

Sort of a thorny problem. I've been digging around on all the PHP forums for a couple of days now, and haven't found anything yet. I'm sure there's someone more experienced than me that can either tell me how to do this, or tell me why it won't work.

Thanks for your feedback! p r i n t e l e c t r i c

laserlight

I think the real problem is that $_POST is undefined within my function, but I would really like some clarification on that.

The $_* superglobal variables are just that - superglobal.
Their scope extends to all functions.

printelectric

I apologize - what I should have said is that $POST is unset, not undefined. The important thing is that when calling a function from a form, I have as of yet been unable to retrieve user supplied values from $POST. I have had no problems doing the same thing if my form submits to a separate PHP page with the same function on it.

dalecosp

Originally posted by printelectric
Yeah. I've tried this about 50 different ways now. I think the real problem is that $_POST is undefined within my function, but I would really like some clarification on that.

I don't know if $_POST should be defined the instant that the user clicks "submit", or if it only becomes defined as something gets submitted to the server for processing.

In response to your comments, I've stripped out all of my SQL interaction, because that's all working fine. I basically am just trying to establish two things:

1) Can I call a function from a form in this way:
<form action="<?php return someFunction(); ?>">

Yes, but keep in mind that the browser expects some HTML within those quotes, so the function must not just return a value, but must echo() or print() it out ... or else you must echo the function <?>

2) Within said function, should I be able to access values from $_POST?

As Laserlight said, yes, of course...

The goal of this, ultimately, would be to put together an SQL query within the function, update the database with the user supplied values, and conditionally send back a URL for the browser (that would be the return value of the function).

Which is all good and well, but, as you have noticed, the server isn't going to act on anything until it is POSTed by submission of the form ... so, as long as the POST information is coming from the PREVIOUS page, you're in the clear, but it sounds as if you are trying to do something a little fishy there ...

PHP is server side, as you either already know or are now learning. Am I reading you wrong here, or are you trying to call a php function with data that hasn't yet been submitted? (I am fairly dense, as most of the regulars 'round here could attest 😉 )

printelectric

"...trying to call a php function with data that hasn't yet been submitted?"

I think that is indeed my problem. I'm very new to server side programming, so there are some very basic things that I'm still trying to figure out. I've decided to abandon this approach, as there are lots of other ways to skin the cat, and I think I've wasted enough time here.

Thanks everybody for your feedback.