[RESOLVED] header() fatal error

ajcether

So basically my problem is this message:

Warning: Cannot modify header information - headers already sent by (output started at /.../index.php:83) in /.../Controller.class.php on line 61

I've looked up what I should do about this, and the answers all tell me that I can only set my headers once. The problem is that I am using a template (I'm using dreamweaver) that the entire site has to use. By copying this template and changing a couple lines, I've figured out that if I comment out:

<?php include("includes/site_header.html"); ?>

in my code (which sets up the top of my page to look the same as every other page on the site; so it must stay), then I stop getting the error. Also, if I just move the code that has the header() call in it to the top of my code then it works, which makes sense...but then it's located at the top left corner of the page rather than in the pagecontainer it should be in.

So, is there something in the site_header.html that I could change to fix this? Or maybe just something I can do instead of using header()?

Here is the necessary code:

index.php:

<body>
<div id="pagecontainer">
<?php include("includes/UWheader_feedback.html"); ?>

<div id="primarycontent">
<?
      include ('Controller.class.php');
?>
</div>
</div>

Controller.class.php:

function form() {
....

 if($fb->valid()) {
$_SESSION['feedback'] = $fb;
return header('Location: ?action=preview'); // This is where the error comes from.
  }

NogDog

The short version is: nothing can be output to the client before any header() command. This means either arranging your application logic/flow to determine what headers need to be sent and execute the header() calls before any output is generated (including anything outside of <?php...?> tags including white-space), or else using output buffering (see [man]ob_start[/man]) and don't flush the buffer until after all header() commands (or just flush automatically at the end of the script). The output buffering method may be easier to implement, but does add some performance overhead - though usually fairly insignificant.

ajcether

Thanks for your response.

My main problem is that I can't change where the header call is taking place....if I make it the first output on the page then it's not longer positioned correctly in the template (it should be under the top banner and beside the sidebar; if I were to display the header() call first, it goes above the top banner and sidebar).

How would I use the output buffering? I put ob_start() and ob_end_flush(); right before and after the header() call, but nothing's changed.

Maybe I will just have to split these into 2 separate pages so I don't need to redirect using header()?

leatherback

ehm.. You have me confused.. Why can't you place the header() call before the top banner and sidebar? As you are not staying on the page anyway..

You de realize that a header() command forces a complete reload of your page right? I tells your browser to go to a new page, afaik

ajcether

Okay...let me clarify what the site is. This is basically just a feedback form. index.php includes the Controller class, which controls everything. The site is initially a form that has fields for Name, Comments, Email. The user is to input their info and then hit the 'preview' button. Once this is done, the page should reload with the user's info recapped in the "primarycontent" section of the page (if I place the header() call before the sidebar and banner, the info shows up in the very top left corner of the page...completely out of place...I've tried it).

NogDog

All HTTP headers get sent -- and must get sent -- to the client before any content. If you are unwilling or cannot figure out how to change the processing flow of your script to accommodate this requirement, then the only other option is to implement output buffering. This can be implemented simply by making the very first line of the main script:

<?php
ob_start();

ajcether

So I fixed my problem by using $this->render(...) instead of header. This doesn't change the url in the nav though...is there anyway to do this in php? So, for example, when I preview the info, the url will include 'preview' somewhere? i know the header() function did this, but I am not using it anymore.

leatherback

If you are concernaid about the URL, why don't you just send them to a different page?

ajcether

Well i could...I just think that would be a lot of work wouldn't it? how would I send all the form information across different pages?

ajcether

I'm just going to leave it as is...it's working properly, the url doesn't really matter