Removing an array from a session array

Question

I am building a shopping cart using session variables. I can push the array to the session array like this:

//initialize session cart array
$_SESSION['cart'] = array();
//store the stuff in an array
$items  = array($item, $qty);
//add the array to the cart
array_push($_SESSION['cart'], $items);

So far, so good. The problem is in removing an item from the cart. When I try to use this, I get a array to string conversion error.

//remove an array from the cart
$_SESSION['cart'] = array_diff($_SESSION['cart'], $items);

To clarify, the question here is why is the above statement creating an array to string conversion error?

possible duplicate of stackoverflow.com/questions/3600750/… — Dan O
– Dan O, Commented Aug 15, 2014 at 0:00
any reason to use array_push over $_SESSION['cart'][]= $items; — user557846
– user557846, Commented Aug 15, 2014 at 0:01
Not so fast -- not a duplicate at all. Check your info before posting. — user1780242
– user1780242, Commented Aug 15, 2014 at 0:02
" Note: If you use array_push() to add one element to the array it's better to use $array[] = because in that way there is no overhead of calling a function. " — user557846
– user557846, Commented Aug 15, 2014 at 0:12

RiggsFolly · Accepted Answer · 2014-08-15 10:12:08Z

2

How about storing an array of objects like this. In my opinion it is a lots easier to read the code this way than addressing arrays within arrays

$item = new stdClass();
$item->id = 99;
$item->qty = 1;
$item->descr = 'An Ice Cream';
$item->price = 23.45;

$_SESSION['cart'][$item->id] = $item;

To remove an items from the cart

unset($_SESSION['cart'][$item]);

To re-access the items data

echo $_SESSION['cart'][$item]->id;
echo $_SESSION['cart'][$item]->desc;
echo $_SESSION['cart'][$item]->price;

Or even

$item = $_SESSION['cart'][$item];
echo $item->id;
echo $item->desc;
echo $item->price;

Or even better

foreach ( $_SESSION['cart'] as $id => $obj ) {
    echo $id ' = ' $obj->descr ' and costs ' . $obj->price;
}

To change existing info

$_SESSION['cart'][$item]->qty += 1;

or

$_SESSION['cart'][$item]->qty = $newQty;

edited Aug 15, 2014 at 10:12

answered Aug 15, 2014 at 0:30

RiggsFolly

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7 Comments

user1780242 Over a year ago

Can you add methods to your object and still store it as a session variable?

RiggsFolly Over a year ago

No I am afraid not. But if you actually created an class you can save the properties of the object to the session and then reconstitute the object by re-instantiating the class and then rehydrating the properties from a $_SESSION variable. You just do $_SESSION['cart'] = serialize($cartObj); See this documentation

user1780242 Over a year ago

That's what was screwing me up originally then. I started out trying to use an object but had errors because the object had methods. I finally ended up doing this, foreach($_SESSION['cart'] as $k => $v) { if ($v == $itemID) unset($_SESSION['cart'][$k]); } which works, but I'm still wondering why I was getting the conversion error with array_diff();

RiggsFolly Over a year ago

Do a print_r(array_diff($_SESSION['cart'], $items)); like I suggested earlier. I bet it does not look deep enough into the arrays to do what you hoped.

RiggsFolly Over a year ago

You might try array_diff($_SESSION['cart'][], $items) that might work.

|

score 1 · Accepted Answer · 2014-08-15 00:24:34Z

1

i suggest this approach

$_SESSION['cart'] = array();

to add an item

$_SESSION['cart'][$item]= $qty;

then use the items id to manipulate:

delete:

unset($_SESSION['cart'][$item]);

change to known qty value:

$_SESSION['cart'][$item]= $qty;

add one:

$_SESSION['cart'][$item] += 1;

multiple variables for an item:

$_SESSION['cart'][$item]= array('qty'=>$qty,$descrip,$size,$colour);

edited Aug 15, 2014 at 0:24

answered Aug 15, 2014 at 0:15

user557846

1 Comment

user1780242 Over a year ago

And using this method, how would you add additional variables, i.e. $price, $descr, etc.?

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