session variables function ouput = PROBLEM

I enabled sessions by adding a session start function to my wp-config file.

Since then, I have happily been able to pass session variables between pages.

Then came the day that I decided that I needed to store the output of functions into session variables. And that’s where I hit a problem.

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I CAN assign session variables (like 1 or ‘Hello World’)using the following code:

<?php
$_SESSION['JoeCatID'] = 1;
?>

I can then retrieve it on another page using this code:

<?php
echo $_SESSION['JoeCatID'];
?>

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PROBLEM

but when I attempt to call a function and assign the function output into the session variable, like so:

<?php
$_SESSION['JoeCatID'] = get_query_var('cat');
?>

I am no longer able to retrieve the session variable on another page (using the same retrieve code above).

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WEIRD SYMPTOMS WHICH MIGHT HELP
– I am able to assign and retrieve the function assigned session variable, if I assign & retrieve at the same time on one page load (place both functions on page).

– but if I try to assign on one page, and then retrieve on another (with the session variable retrieve), the variable does not return properly.

– If the function returns an INT (like get_query_var(‘cat’)), on next page, it returns a “0”.

– If the function returns a string (like category_description()), on next page, it returns nothing (blank).

– I even tested by assigning the function assigned session variable on Page 1, reloading Page 1 (to assign it); I then removed the assignment call, and replaced it with the retrieve call, and it fails.

– so regardless of whether I call it on the Same Page, or a new page, the session is failing when I try to retrieve a function assigned session variable AFTER the Page Load.

– however (as I said above) it works perfectly when I assign, and then try to retrieve a non-function variable (like 1 or ‘Hello World’).

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Those are all the details about the issue. I’ve been working for 2 days straight, but I can’t seem to resolve it.