Return array key via array value in multiple array data

Question

My $_SESSION stores array in the format below. All of productId value are unique. I want to get array key using a productId.

Array
(
[0] => Array
    (
        [productId] => 3
        [productQuantity] => 1
    )

[1] => Array
    (
        [productId] => 4
        [productQuantity] => 1
    )

[2] => Array
    (
        [productId] => 5
        [productQuantity] => 1
    )

)

I have tried array_search but its not working. I actually saw a similar question, but the answer was left untold. This is the code i tried but its not displaying anything:

$key = array_search(3,$_SESSION['cart']);
echo $key;

AbraCadaver · Accepted Answer · 2018-05-25 17:55:37Z

1

Since they are unique just re-index by the productId:

$cart = array_column($_SESSION['cart'], null, 'productId');
echo $cart[3]['productQuantity'];

Or:

echo array_column($_SESSION['cart'], null, 'productId')[3]['productQuantity'];

If you'll only ever have those 2 then it makes sense to extract productQuantity and re-index by productId:

$cart = array_column($_SESSION['cart'], 'productQuantity', 'productId');
echo $cart[3];

The array will look like $cart = [3 => 1, 4 => 1, 5 => 1].

Or:

echo array_column($_SESSION['cart'], 'productQuantity', 'productId')[3];

If you really just want the current key for some reason, extract productId and search that (as long as keys are 0 based and sequential:

$key = array_search(3, array_column($_SESSION['cart'], 'productId'));

edited May 25, 2018 at 17:55

answered May 25, 2018 at 17:38

AbraCadaver

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5 Comments

john godstime Over a year ago

Thanks for the contribution, but this did not actually work. 1 only want to get the key of the array by the productId. like productId 3 has the key 0, productId 4 has the key 1. When i supply the productId, it should give me only the key associated to that productId.

AbraCadaver Over a year ago

I understand that but why? What is the end goal to getting the key?

john godstime Over a year ago

i want to update productQuantity value using the key

AbraCadaver Over a year ago

I edited, but it would be much easier to use the productId as the key wouldn't it??? Yes, it would.

AbraCadaver Over a year ago

Yes I caught that. Still, take some seasoned advice as use id as the key.

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