[RESOLVED] Yet another sessions question

Ron_Austin

I would like to know how to pass variables from page to page

I thought the code below should work, but I get no output. There are 4 pages; the first (not shown) gathers data

The second page examines the data and directs you to one of two other pages (depending upon the selections).

The last page acts on the data. The problem is that the data does not get passed from the second page to the last page.

Can someone please tell me what is wrong with this code?

page 2

<?php
session_start();
$tweet_type=$_POST['tweet_type'];
$tweet=$_POST['tweet'];
$categ=$_POST['category'];

$_SESSION['category']=$_POST['category'];
$_SESSION['type']=$tweet_type;
$_SESSION['tweet']=$tweet;
$_SESSION['categ']=$categ;

if ($tweet_type=="write"){
header("Location: http://www.xxx.com/twitter/write_a_tweet.php") or die(mysql_error());
exit;
}
elseif ($tweet_type=="pick"){
header("Location: http://www.xxx.com/twitter/pick_a_tweet.php") or die(mysql_error());
exit;
}
?>

last page
http://www.xxx.com/twitter/pick_a_tweet.php

<?php
session_start();
$category=$_SESSION['category'];
$tweet_type=$_SESSION['type'];
$tweet=$_SESSION['tweet'];
$categ=$_SESSION['categ'];


echo "category $category<br>";

echo "type $tweet_type<br>";

echo "tweet $tweet<br>";

echo "categ $categ<br>";




echo "PICK A TWEET";

?>

Ron Austin
Forum Newbie

Posts: 1
Joined: Mon Feb 06, 2012 10:54 pm

Top

123

A good way to debug this will be to use your session variable in the if statement on page 2 and if you do not get redirected to the next page then your session variable is empty.

if ($_SESSION['type']=="write"){
header("Location: http://www.xxx.com/twitter/write_a_tweet.php") or die(mysql_error());
exit;
}

or you could try putting this into the last page to see what variables are available

//check available variables on page
var_dump(get_defined_vars());

Good luck
🙂

Ron_Austin

123;10996096 wrote:
A good way to debug this will be to use your session variable in the if statement on page 2 and if you do not get redirected to the next page then your session variable is empty.
if ($_SESSION['type']=="write"){
header("Location: http://www.xxx.com/twitter/write_a_tweet.php") or die(mysql_error());
exit;
}
or you could try putting this into the last page to see what variables are available
//check available variables on page
var_dump(get_defined_vars());
Good luck
🙂

I followed your suggestions, and substituted

if ($_SESSION['type']=="write") on page 2 and it did recognize the variable there and took me to the next page. The dump on that page showed that all the variables= NULL.

The question of course, is Why? Why is it not passing the variables to the next page? This is my first attempt at php programing and it is very frustrating to say the least.

Derokorian

Is the last page on the same domain as page2? If the subdomain differ or anything the cookies will be set for page2 but not the last page. for example is page2 is at domain.com while the last page is at admin.domain.com it won't work. See http://us2.php.net/manual/en/function.session-set-cookie-params.php for more information if this is the problem.

Also do you have error_reporting set to E_ALL ? Just to make sure your not missing some error (such as white space output before session_start which would cause it to fail)

bradgrafelman

Derokorian;10996105 wrote:
Also do you have error_reporting set to E_ALL ? Just to make sure your not missing some error (such as white space output before session_start which would cause it to fail)

^ This was going to be my response, in addition to verifying that you've got display_errors (or log_errors) set to On and that you're checking for any and all PHP error messages.

Also, you could use [man]session_id/man to output the session ID on the two separate pages to check if it is getting propagated correctly. If it is, then you'll see the same value on both pages. If it isn't, then the value will change (meaning your previous session was lost and PHP started a brand new one).

Ron_Austin

Derokorian;10996105 wrote:
Is the last page on the same domain as page2? If the subdomain differ or anything the cookies will be set for page2 but not the last page. for example is page2 is at domain.com while the last page is at admin.domain.com it won't work. See http://us2.php.net/manual/en/function.session-set-cookie-params.php for more information if this is the problem.

Also do you have error_reporting set to E_ALL ? Just to make sure your not missing some error (such as white space output before session_start which would cause it to fail)

All pages are in the same folder on the same domain. My error log shows no errors after I run the script.

How do I set the error_reporting to E_ALL?

I start the script and then start the session so there is no other output first.

I tried to use cookies and that didn't work either.

What else could be wrong or what else can I do to pass variables from one scipt to another one?

bradgrafelman

Ron Austin;10996124 wrote:
How do I set the error_reporting to E_ALL?

See [man]configuration.changes[/man] and [man]error_reporting[/man] in the PHP manual for some options of where/how you can set this.

EDIT: Forgot to mention... you should do this first before attempting any further debugging; it would be quite silly to waste your time (and ours!) trying to debug issues when PHP is trying to output helpful error messages that are being masked by the current error_reporting level.

Ron Austin;10996124 wrote:
I start the script and then start the session so there is no other output first.

There might not be any other intentional output, sure, but are you positive that there is no unintentional output (such as any whitespace before the first <?php opening tag)?

Ron Austin;10996124 wrote:
I tried to use cookies and that didn't work either.

Either you tried to use them incorrectly, or else there is a larger problem at hand (such as data being sent as output before you attempted to set the cookie).

Ron Austin;10996124 wrote:
What else could be wrong or what else can I do to pass variables from one scipt to another one?

See my debugging technique above in regards to verifying that the session ID is propagated from one page to the next.

You could also take a look at the raw HTTP headers being sent in reply by the server for both page requests; if you don't see the Set-Cookie header, then something (such as data being sent as output, causing HTTP headers to be sent at that point) is preventing PHP from altering the HTTP headers to set the cookie.

Also, could you do a [man]phpinfo/man and show us the values of the PHP directives prefixed with 'session.' ?

Ron_Austin

session
Session Support enabled
Registered save handlers files user sqlite
Registered serializer handlers php php_binary wddx

Directive Local Value Master Value
session.auto_start Off Off
session.bug_compat_42 On On
session.bug_compat_warn On On
session.cache_expire 180 180
session.cache_limiter nocache nocache
session.cookie_domain no value no value
session.cookie_httponly Off Off
session.cookie_lifetime 0 0
session.cookie_path / /
session.cookie_secure Off Off
session.entropy_file no value no value
session.entropy_length 0 0
session.gc_divisor 100 100
session.gc_maxlifetime 1440 1440
session.gc_probability 1 1
session.hash_bits_per_character 5 5
session.hash_function 0 0
session.name PHPSESSID PHPSESSID
session.referer_check no value no value
session.save_handler files files
session.save_path /tmp /tmp
session.serialize_handler php php
session.use_cookies On On
session.use_only_cookies Off Off
session.use_trans_sid 0 0

bradgrafelman

Looks pretty standard, so we can probably rule out a configuration issue.

Ron_Austin

I found this in the php.ini file

error_reporting = E_ALL & ~E_NOTICE

I plead ignorance to the suggestion that I check the headers. I don't have a clue how to do that.

Ron_Austin

I created two more scripts to make this as simple as I can.

When I execute atest1.php the screen displays

category =
test = this is a test

//atest1.php
<?php
session_start();
$_SESSION['category']="session test";
header("Location: http://www.xxx.com/twitter/atest2.php");
?>

//atest2.php
<?php
session_start();
$category=$_SESSION['category'];
$test="this is a test";
echo "category = $category<br>";
echo "test = $test<br>";
?>

bradgrafelman

Ron Austin;10996137 wrote:
I found this in the php.ini file

error_reporting = E_ALL & ~E_NOTICE

Try changing that to just E_ALL.

Ron Austin;10996142 wrote:
I created two more scripts to make this as simple as I can.

For the first script, try adding a [man]session_write_close/man just to make sure PHP is saving the session contents to disk before the redirect occurs.

Also, try removing the redirect and replacing it with a simple link to page 2. Then, output the session ID on both pages (see [man]session_id/man) and see if that value changes from one page to the next.

Ron_Austin

Well I took a little break from my problem of loosing variables, but started again tonight and came across a post saying that you should not use the full URL (http://www.xxx/twitter/prog.php), but rather just use: prog.php. I tried that and it worked.

Now that I have got past that hurdle, I will probably have some more questions later.

bradgrafelman

Ron Austin;10996455 wrote:
came across a post saying that you should not use the full URL (http://www.xxx/twitter/prog.php), but rather just use: prog.php.

Well then you managed to find a post with bad advice, since that violates the RFC document that describes the 'Location' HTTP header (which must contain a full URI). In addition, it doesn't teach you why it was broken before.

For the latter, note that by default cookies are set for the exact host name that you used to visit the page. Note that 'www.mysite.com' and 'mysite.com' are not not the same host name, thus if you visited the site with the latter but encountered a redirect aimed at the former, you should expect to lose the session cookie.

To change this, you'd either need to a) use $SERVER['SERVER_NAME'] (or perhaps $SERVER['HTTP_HOST']) to determine which host was used to reach your site, or b) modify the session.cookie_domain PHP directive to look like ".mysite.com" (where the initial "." will cause the cookie to be set for all subdomains of "mysite.com").