Redirect in general

gregh

Say in the middle of a script, you want to redirect to another page or script. For example:

<?
if($a) {
// get something from the database
} else {
// redirect to another .php page, for
// instance, back to the original form
}
?>

What documentation heading would this redirection be described under, within the main php document? Thoughts? Thanks in advance...

gregh

I've found that you can use the following:

header("Location: http://www.espn.com");
exit;

But it seems that you can only use that at the beginning of the page because otherwise the header is already printed, and thus cannot be accessed from the end of the script. Any thoughts on how to perform redirects further down in your .php page?

polson

You have several options, here are some :

Eliminate output before it reaches this point.
Seperate script into multiple pages
Use output buffering :
http://www.zend.com/zend/art/buffering.php
http://phpbuilder.com/columns/argerich20010125.php3
Use HTML :
<META HTTP-EQUIV="REFRESH" CONTENT = "0; URL=http://www.example.com/">

But keep in mind, you can use code before calling header() but just not output of data. So, doing if/else , $var = 'foo'; , etc. is okay to do before hand, but echo 'foo' is not. P.s. you can use javascript too but don't.

yelvington

Do not confuse "beginning of page" with "before sending any content." So long as you don't send data to the browser, you can have 20K of PHP code, database queries, whatever, before calling header().

mthompson_1

Since there is not a "Response.Redirect" as I assume your trying to mimmick (i.e. ASP), here's a small jscript that you can place in an include file, and call the function in your page:

<?php
// function redirect
// Author: Michael Thompson
// 2001 July 10
// License: GNU General Public License
function redirect($URL)
{

echo "<script language='javascript'>";//
echo "function redirect(url){" ;
echo "document.location.href=url;}";
echo "redirect($URL)";
echo "</script>";
}
//call the redirect function passing it the url
redirect("'http://atonix'")//notince the single quote inside the double quote
?>

// This was a GOOD Question you have...
// I hope this helps.

polson

I disagree with using javascript, use HTML or PHP instead. Regarding Response.Redirect, use HTML meta refresh as everyone has HTML enabled, not javascript.

mthompson_1

I agree with you philip, and respect your opinion fully. As a developer you want to cover every possible area, and script-disabled browsers could break the jscript redirect function, completely abandoning the user.

I just wanted to address how to use javascript do cause a redirect effect in the middle of a page after the headers have been written, which Greg addressed in the second thread.

I've included examples of what philip has addressed as alternatives and a more safe and reliable way of redirecting a user to another page.

Remember that header() function works just as the Response.Redirect function does in JSP and ASP. So we can’t modify the HTTP status and add a header to the response after the body has gone. So if we add anything to the HTML output stream, calling the header() function will result in an ERROR.

Michael

<?php
//function navigate
// Author: Michael Thompson
// 2001 July 10
// License: GNU General Public License
function navigate($url)
{

header("Location: $url");
exit;
}
navigate("http://www.phpbuilder.com")
?>

////////////////////////////////////////////

<?php
// function page_meta
// Author: Michael Thompson
// 2001 July 10
// License: GNU General Public License
function page_meta($url)
{

$action = "<META HTTP-EQUIV='refresh'
content='1; URL=$url'> ";
echo $action;
}

?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<head>
<title>Untitled</title>
<?php page_meta("http://www.linux.com") ?>
</head>

<body>

Anon

I don't see the point to any of this. Structure your code properly. Send headers before sending body content. HTTP specifies the Location: header for redirects; use it.

<? header('Location: /mypage.php'); >

Anon

Thanks, I needed to redirect as well, and found your ideas very helpful>
Patty

Anon

Technically speaking, you should do three things. a) Send a location header, b) send the meta tag and c) include a hyperlink...Using the Locaion: header causes a 302 Found to occur. Here is what W3C has to say about 302s:

10.3.3 302 Found

The requested resource resides temporarily under a different URI.
Since the redirection might be altered on occasion, the client SHOULD
continue to use the Request-URI for future requests. This response
is only cacheable if indicated by a Cache-Control or Expires header
field.

The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the
response SHOULD contain a short hypertext note with a hyperlink to
the new URI(s).

I use this function for redirection, which must be called before headers are sent:

//Redirect: takes a url and writes a re-direct page...starting with header redirect, then a meta tag, and finally a link:
//Note: no actuall data can be sent before this, or header update will fail
function redirect($url) {
header("Location: $url");
print "<head><meta http-equiv=\"Refresh\" content=\"0; URL=$url\"></head><body>If your browser does not forward you, <a href=\"$url\">click here</a>.</body>";
}

Netscape 3 Windows, for instance, does not listen to the "Location:" header but does (I think) respect meta refresh tags...if all else fails, you have a hyper-link so your user will never be stranded. Note that sending body content AFTER the header isn't a problem, furthermore, most browsers will forward the user without bothering to render the page. Hope this helps.

Anon

Don't know whether this thread is abandoned or not, but anyway:

I need to redirect the entire document while inside a particular frame. I'd like this solution to work for as many browsers as possible. In Javascript this is trivial, but I'd like to stay away from Javascript.

Basically what I need is a combination of

<META HTTP-EQUIV="Window-target" CONTENT="_top">
and
header ("Location: http://foo.com/");

Is there a way to do this just with the header? META HTTP-EQUIV tags don't work with all browsers.

Thanks!

Anon

The "Redirect" you have mention here is redirect as the HTML header function. How a bout after proccessing data, I want to redirect to a url with info like:

/ before this, you may need to login, then i will check the login data from database, and lastly redirect automaticly to other url /

http://www.http://www.phpbuilder.com/forum/read.php3?num=2&id=153224&thread=122991

Anon

I got another one.. I have a little PHP script I want to run first and then redirect people to a file they want to download.

The <META> does something but seems to get stuck in a loop.
The "header" option works fine but opens the .zip file it opens as page content.

How to tackle this?

Anon

It works

boototter

THIS advice, the use of the meta-tag was exactly what I was looking for.

it works with an if-elseif-else situation, and can redirect to a 404 page for those not authorized even to know the existence of a page, leaving headers used for those who may intact.

no traceable scripts needed, so no problem on them blocked.

Thanks!
David

philip olson wrote:

You have several options, here are some :

Eliminate output before it reaches this point.
Seperate script into multiple pages
Use output buffering :
http://www.zend.com/zend/art/buffering.php
http://phpbuilder.com/columns/argerich20010125.php3
Use HTML :
<META HTTP-EQUIV="REFRESH" CONTENT = "0; URL=http://www.example.com/">

Anon

Well i am glad everyone has learned somthing from all this.... now suppose you are working with html templates and cant add header fields and cool js to the body field. I need a simple get url type function that i can call when certain messages arew echoed. ie: 2 text fields both with validation...

if ($name == "") {
die("<br><br>

Please enter your name!

You will be redirected to your previous page in
a moment................

if you are not redirected or do not wish to wait <a href=javascript:history.go(-1)>click
here</a>");

$url= "guestbook-sign.php";
go_url($url);

}

how do i do this.. thanx