how to create aspx's postback effect in PHP

shuffle · June 16, 2011

Hello,

I'm trying to create aspx's postback effect in PHP. This can be done with javascript with the use of a hidden "viewstate" (aspx generated) variable. Viewstate preserves the state of a page (input text in text boxes stay the same) when a form action has been submitted.

So what I'm trying to preserves inputted/selected text and display new information based on that inputted/selected text when a form action has been submitted.

Here is basic example for what I want to recreate in PHP (generated from aspx):

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>
Untitled Page
</title></head>
<body>
    <form name="form1" method="post" action="default.aspx" id="form1">
<div>
<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
<input type="hidden" name="__LASTFOCUS" id="__LASTFOCUS" value="" />
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUINTEwNDE4MTBkZEUojnNucBpb9SAjxDe4Z6ZI/m7G" />
</div>

<script type="text/javascript">
//<![CDATA[
var theForm = document.forms['form1'];
if (!theForm) {
    theForm = document.form1;
}
function __doPostBack(eventTarget, eventArgument) {
    if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
        theForm.__EVENTTARGET.value = eventTarget;
        theForm.__EVENTARGUMENT.value = eventArgument;
        theForm.submit();
    }
}
//]]>
</script>


<div>

<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWBQKH453zCwKd5I/lCgKxx4CJAgLlwPXgBwKO7fe5AhVWST46gYYuNp7aSlVEEFAP5t5Y" />
</div>
    <div>
    
        <select name="DropDownList1" onchange="javascript:setTimeout('__doPostBack(\'DropDownList1\',\'\')', 0)" id="DropDownList1">
<option selected="selected" value="first">first</option>
<option value="second">second</option>

<option value="third">third</option>

</select>
    
    </div>
    </form>
</body>
</html>

Thanks

Jeffro · June 16, 2011

oops.. i retract my answer as it didn't answer the "viewstate" dilemna.

shuffle · June 20, 2011

I'm still looking for a solution. Anyone got any ideas?

trq · June 20, 2011

You could always store a copy of the $_POST array into the users $_SESSION array (or even just the values you want) when the form has been submitted then easily restore them from there.

shuffle · June 20, 2011

well yeah I could do that but I don't want to reload the page. I'm looking to only refresh one part of the page for the information selected. I need javascript to do it but there is a part missing that I don't know how to do.

Here is an example of what I'm trying to do. Just select different items in the dropdown-list to see what I'm talking about

http://demo.koolphp.net/Examples/KoolComboBox/Advances/AutoPostback/index.php

KevinM1 · June 20, 2011

It's just a simple JavaScript form submission that fires on the <select> element's onchange event. To do it without a page refresh, use AJAX during the event instead of a 'normal' submission.

And, just to be clear about ASP.NET's postback/viewstate capabilities, postback works almost exactly how thorpe's suggestion works. Hidden inputs are injected into the page. The viewstate is simply a base-64 encoded string containing the values of the server control properties on the current page. This encoded viewstate meta-value is set as the value for one of the hidden inputs, where it is decoded and parsed on the back end during page rendering. For more, see: http://msdn.microsoft.com/en-us/library/ms972976.aspx

You can do essentially the same thing with PHP and hidden inputs, with the added benefit of not having to concern yourself with ASP.NET's horrid page lifecycle.

shuffle · June 21, 2011

Ok I'll try to do that. I'll have to learn more AJAX as I only have a rough understanding of it.

Thanks for you help.

shuffle · June 22, 2011

Well, I'm still not getting much further with this as i thought. If its not to much trouble can some one post some basic example code for doing this?

shuffle · June 23, 2011

Here is my attempt at getting this working. So far no luck.

I'm just gonna post the relevant code.

<script>
function getXMLHTTP() { //fuction to return the xml http object
	var xmlhttp=false;	
	try{
		xmlhttp=new XMLHttpRequest();
	}
	catch(e)	{		
		try{			
			xmlhttp= new ActiveXObject("Microsoft.XMLHTTP");
		}
		catch(e){
			try{
			xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
			}
			catch(e1){
				xmlhttp=false;
			}
		}
	}
	return xmlhttp;
}


function searchDate(strURL) {		

	var req = getXMLHTTP();

	if (req) {

		req.onreadystatechange = function() {
			if (req.readyState == 4) {
				// only if "OK"
				if (req.status == 200) {						
					document.getElementById('recordTable').innerHTML=req.responseText;						
				} else {
					alert("An error occurred:\n" + req.statusText);
				}
			}				
		}			
		req.open("GET", strURL, true);
		req.send(null);
	}
}
</script>

<form action="" method="post">
<p>Date:<input type="date" name="selectedDate" size="10" />
<input type="submit" name="submit[searchDate]" value="Recherche" onclick="searchDate('planification.php?selectedDate='+document.getElementById('selectedDate').value)" style="margin-right: 25%;" />
<div id="recordTable">
</div>

planification.php

        $stmt->bind_param("s",$selectedDate);
$stmt->execute();
//variables are binded and displayed in the same order as the select query
$stmt->bind_result($a, $b, $c, $d, $e, $f, $g, $h, $i, $j, $k, $l, $m, $n, $o); 

    $planificationTable = '<table border="1"><th>a</th><th>b</th><th>c</th>
<th>d</th><th>e</th><th>f</th><th>g</th><th>h</th><th>i</th>
<th>j</th><th>k</th><th>l</th><th>m</th><th>n</th>
<th>o</th>';
    
while($stmt->fetch())
	$planificationTable .= '<tr><td>' . $a . '</td><td>' . $b . '</td><td>' . $c . '</td><td>' . $d . '</td>
	<td>' . $e . '</td><td>' . $f . '</td><td>' . $g . '</td><td>' . $h . '</td><td>' . $i . '</td>
	<td>' . $j . '</td><td>' . $k . '</td><td>' . $l . '</td><td>' . $m . '</td><td>' . $n . '</td>
	<td>' . $o . '</td></tr>';

$planificationTable .=  '</table>';
print $planificationTable;

shuffle · June 28, 2011

I still can't find a solution for this. Anyone?

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