Assign Session Variables: Best Practices

[StevenOliver]

Scenario: My page generates several PHP variables. Some of those variables get posted to another page.

Question: If a variable is to be assigned to a Session, is there any reason to assign this value to a regular PHP variable?

Example: When an API generates a "shipping label tracking number, which is better, "A" or "B" or subtle variation "C":

A.) 
$result = json_decode(curl_exec($ch));
$_SESSION["trackingNumber"] = $result->parcelTrackingNumber;

... and then use $_SESSION["trackingNumber"] throughout the rest of my script (like this: echo  "Hello, here's your tracking number: ".$_SESSION["trackingNumber"]).

B.) 
$result = json_decode(curl_exec($ch));
$trackingNumber = $result->parcelTrackingNumber;
$_SESSION["trackingNumber"] = $trackingNumber;

... and then use "$trackingNumber" throughout the rest of my script (like this: echo  "Hello, here's your tracking number: ".$trackingNumber).

C.) 
$result = json_decode(curl_exec($ch));
$_SESSION["trackingNumber"] = $result->parcelTrackingNumber;
$trackingNumber = $_SESSION["trackingNumber"];

... and then use "$trackingNumber" throughout the rest of my script (like this: echo  "Hello, here's your tracking number: ".$trackingNumber).

Thank you! I've always wondered about this. Which is best?

 

 

[requinix]

There are basically two philosophical reasons you would consider the variable:

1. You don't want to type $_SESSION["trackingNumber"] everywhere. B/C are identical.

2. You need the value in the script but also need it in the session. B is more suggestive of that (you need the value later, adding it to the session is a secondary concern) but C is perfectly fine too, it's a negligible difference.

If neither of those apply then you might as well just stick with A.

[kicken]

B/C can be instead written as:

$result = json_decode(curl_exec($ch));
$trackingNumber = $_SESSION["trackingNumber"] = $result->parcelTrackingNumber;

Creating a different local variable rather than using the session (or post/get/whatever) array can be useful to reduce typing.  This is the primary reason I do such things from time to time. 

Even with an editor that has good auto-complete it is frequently easier/faster to reference a simple variable rather than an array key.

[StevenOliver]

Thank you both!
I like the "$trackingNumber = $_SESSION["trackingNumber"] = $result->parcelTrackingNumber;" line of code!

I remember back in 1999 when server RAM was at a premium... assigning variables when not absolutely necessary was a no-no. And, when Sessions were invented, they made your page really, really slow. LOL