How can I get an object “key” from the value? Is there something like array_search for objects?

Question

I have a class like so:

stdClass Object
(
    [id] => 1
    [items] => stdClass Object
        (
            [0] => 123
            [1] => 234
            [2] => 345
            [3] => 456
        )
    )
)

Let's call the above object $foo .

Let's say $v = 234 . Given $foo and $v , how can I return the "key" 1 ?

If $foo->items was an array I would simply do $key = array_search($v,$foo->items); . But this doesn't work in an object.

How can I find the key for $v without looping through the object in some foreach ?

Answer 1

Use get_object_vars and search through the array returned.

Reference : http://php.net/manual/en/function.get-object-vars.php

Here's an example of how to search through the array returned for a key:

<?php
$foo = NULL;
$foo->id = 1;
$foo->items = array(123, 234, 345, 456);
$foo_array = get_object_vars($foo);
print_r($foo_array);

foreach ($foo_array as $key => $value) {
    if ($value == 1) {
        echo $key;
    }
}
?>

Output:

Array
(
    [id] => 1
    [items] => Array
        (
            [0] => 123
            [1] => 234
            [2] => 345
            [3] => 456
        )

)
id

CodePad : http://codepad.org/in4w94nG

Answer 2

As you have shown in your example, you're dealing with stdClass object(s). Those are quite similar to arrays and with PHP you can easily convert between those two with something called casting :

$object = $foo->items;
$key = array_search($v, (array)$object);
                        ^^^^^^^--- cast to array

As this little example shows (I just used the $object variable to make the cast more visible, you normally can write it as one-liner), the cast from object to array does allow you to use the known function ( array_search ) on the object.

Because arrays and stdClass objects in PHP are so similar, this works in both directions:

$array  = ['property' => 'value'];
$object = (object)$array;
echo $object->property; # value

This also works with other types in PHP, so probably apart from your concrete problem, something worth to read about: Type Juggling ^Docs , but take care, that in PHP this has many special rules. But between array and objects, it's pretty straight forward.

Answer 3

$key = array_search($v, get_object_vars($foo->items));

编辑：试试这个