Redirect in PHP

MattyJ

Hi,

I'm new to PHP and am coming as an ASP programmer (though I know c++ and stuff so the syntax isn't a big problem). My current issues involve trying to do many of the things I could do with ASP, but in php now. The one I'm struggling to identify right now is the equivalent of the ASP Response.Redirect() function. Is there an equivalent php function to send my user to a new page through code and how do I use it?

Thanks,

Mat

devinemke

header('location: http://www.MattyJ.com');

MattyJ

Cool, thanks.

I was sure it was going to be easy, but I just couldn't pick it out of the reference lists I was going through.

pohopo

header only works if it is the very first line of code. if you want to use redirect anywhere in the page you need to turn the output buffer on by putting ob_start() at the top of your page and ob_end_flush () at the bottom of your page.

MattyJ

I was just coming back to ask about this.

When you mean that I need to flush at the end of the page, do you mean as the last line of the file, or right before the header command?

devinemke

you should read up on headers.
you can only call the [man]header[/man] function before any output has been sent to the browser. you can control how output is sent to the browser via the Output Control Functions.

pohopo

When you mean that I need to flush at the end of the page, do you mean as the last line of the file, or right before the header command?

The last line of the file.

MattyJ

Now, I want to redirect (or change the header location) after performing a number of operations.

I read the header information, and I get the impression that the output buffer merely stores all the content until the end. if it does that, will the location code happen before or after the code is executed?

Maybe I'm stuck in an ASP mindset, but will the location code wait to run until the browser receives it, at which point the server code has already run?

And if thats the case, does it matter where in the document the location command is located?

Thanks again,

Mat

devinemke

you say you need to "perform a number of operations". if none of these operations involve sending output to the client then you don't need to use output buffering at all. you only need to use output buffering if you need to conditionally send output to the client (usually depending on what happens during the operations).

a simple example: you are collecting input from a form. the form processing script (specified in the action tag of the form) parses through the form data for validation. if the form was not filled out completely then you want to re-direct to a page spitting out an error message. if the form was filled out then you want to stick the form data in a database, send an email, then spit out a "thank you" message. in this scenario you don't really need output buffering because you are not outputing anything until after the form validation. here is sort of pseudo-code:

<?php
$validate = validate_form();

if ($validate)
{
	insert_into_db();
	send_email();
	header('location: http://www.MattyJ.com/thank_you.html');
	exit();
}
else
{
	header('location: http://www.MattyJ.com/error.html');
	exit();
}
?>

notice that there is no output until the header() calls.

MattyJ

That makes sense now. I guess I need to get used to not being buffered as I guess ASP seems to be. I actually was doing everything fine, but had bumped my code into the middle of the HTML because I'd originally planned not to redirect. As soon as I got rid of that, I had no problems, so thank you.

Drakla

devinemke's done it automatically without thinking, but those exits after the header are pretty important, because if you let the code keep going and it stumbles into some output you might yet again receive the 'Error, headers already sent' gripe.

Remember to have absolutely nothing before your opening php tag, either, as that will be classed as output - even a space or return. If you're including any files also check them for errant characters before or after their php tags if you've got one of those "But I'm not ouputting anything!!" type things happening.

You can even die( header('location: somehwere.php') );

MattyJ

Thanks, I think I see how this all interplays.