Rename PHP Object property in foreach loop

Question

I have a PHP object that I need to change the key name of in a foreach loop:

stdClass Object
(
   [first-name] => NAME
   [last-name] => NAME
   [phone-number] => NUMBER
   ...
)

I need to replace the dash '-' to a underscore '_' within a foreach so it looks like this:

stdClass Object
(
   [first_name] => NAME
   [last_name] => NAME
   [phone_number] => NUMBER
   ...
)

I found this post: PHP - How to rename an object property? which does tell me how to do it, the problem is that when I use unset() inside of the foreach it unsets all of the keys instead of just the ones I want it to.

Here's my code:

foreach ($customer as $key => $value) {
    $key2 = str_replace('-', '_', $key);
    $customer->$key2 = $customer->$key;            
    unset($customer->$key);
}

which returns an empty object:

stdClass Object
(
)

How can I unset the original keys without affecting the new ones?

$customer = json_decode(str_replace('-', '_', json_encode($customer))); 3v4l.org/aaXG0 | Good if you're sure that values don't contain dashes. :) — Omi Shah
– Omi Shah, Commented Nov 20, 2022 at 16:57
@OMiShah: Well even if you're sure today, I would not suggest to run this on data which may change over time. OP clearly only wants to map the keys and side effects on data is part of the question already, therefore ... NO (, not sorry :) ). — hakre
– hakre, Commented Nov 20, 2022 at 17:18

hakre · Accepted Answer · 2022-11-20 17:04:03Z

2

There is a simple trick you can do in general and that is only doing the operation if there is a change:

    $key2 = str_replace('-', '_', $key);
    if ($key2 !== $key) {
        $customer->$key2 = $customer->$key;            
        unset($customer->$key);
    }

You just do nothing if the operation has already been done (by the outcome).

Within a foreach this can be further "tweaked" by making use of the continue keyword and inversing the comparison:

foreach ($customer as $key => $value) {
    $key2 = str_replace('-', '_', $key);
    if ($key2 === $key) {
        continue; // nothing to do
    }
    $customer->$key2 = $customer->$key;            
    unset($customer->$key);
}

But at the end of the day you only don't want to delete which equals to always set (which works if you unset first and iterate on a clone):

foreach (clone $customer as $key => $value) {
    $key2 = str_replace('-', '_', $key);
    unset($customer->$key);
    $customer->$key2 = $value;
}

So choose your weapon, there are even more ways to skin this cat, this just for inspiration. At the end of the day the order of the operations (adding, deleting etc.) is the "key" point.

All examples on 3v4l.org.

edited Nov 20, 2022 at 17:04

answered Nov 20, 2022 at 16:38

hakre

200k55 gold badges454 silver badges865 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

KIKO Software Over a year ago

Can you please test your code? It doesn't seem to work.

hakre Over a year ago

@KIKOSoftware: That's unfortunate as its perhaps pseudo code continued from the question. Which one specifically you'd like to see under test? Just so that I can add an online example on 3v4l.org.

KIKO Software Over a year ago

You can use my 3v4l example to test your code.

hakre Over a year ago

@ChristopherAnsbaugh: It did before the edit, yes. That is because foreach'ing the same instance (the one that is modified while iterating, SO reference Q&A), a clone resolves this easily. It requires to unset first IMHO due to how $customer->key on the original may have gone away due to earlier iterations and str_replace resulting in a same key by accident.

KIKO Software Over a year ago

Cloning is a smart idea.

|

KIKO Software · Accepted Answer · 2022-11-20 16:47:25Z

1

You code almost seems to work, but its a bad idea to work on an object you're looping through. The solution is get_object_vars() which can get the properties before you loop:

foreach (get_object_vars($customer) as $key => $value) {
    $key2 = str_replace('-', '_', $key);
    $customer->$key2 = $customer->$key;            
    unset($customer->$key);
}

See: https://3v4l.org/sfZq3

answered Nov 20, 2022 at 16:47

KIKO Software

17.5k3 gold badges33 silver badges53 bronze badges

Collectives™ on Stack Overflow

Rename PHP Object property in foreach loop

2 Answers 2

8 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

8 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related