php unset in array foreach loop creates an object - php

Question

I have a big JSON that looks something like this:
{
"bracers": [
{
"id": "Bracers_208",
"name": "Unearthed Boon"
}
],
"offHand": [
{
"id": "Bracers_208",
"name": "Unearthed Boon"
},
{
"id": "Weapon123",
"name": "Some Weapon Boon"
},
{
"id": "Weapon456",
"name": "Some Other Weapon Boon"
}
],
"mainHand": [
{
"id": "Weapon123",
"name": "Some Weapon Boon"
}
]
}
I decode the JSON like this:
$itemDB = json_decode($json, true);
What I want to do now is to remove all entries from offHand that are already in mainHand. So I loop through both, compare the id and unset() the value if there's a match.
foreach($itemDB['offHand'] as $index => $item) {
foreach($itemDB['mainHand'] as $key => $weapon) {
if($item['id'] == $weapon['id']) {
unset($itemDB['offHand'][$index]);
}
}
}
Then I encode it again:
$newJSON = json_encode($itemDB, JSON_PRETTY_PRINT);
The removal of duplicates works, but the offHand array is changed into an object (or assoc array) that looks like this:
{
"bracers": [
{
"id": "Bracers_208",
"name": "Unearthed Boon"
}
],
"offHand": [
"0": {
"id": "Bracers_208",
"name": "Unearthed Boon"
},
"2": {
"id": "Weapon456",
"name": "Some Other Weapon Boon"
}
],
"mainHand": [
{
"id": "Weapon123",
"name": "Some Weapon Boon"
}
]
}
Why does this happen and how can I prevent it?
Edit:
Just to clarify, if I remove the unset function and just do nothing inside that loops ( or just add a property to the objects), the numbered additional keys in the JSON aren't there and the JSON array is fine. That's why I concluded that unset is causing this.

Answer 1

After you're loop ends, add the following line of code to remove the keys from the offHand array element:
$itemDB['offHand'] = array_values($itemDB['offHand']);

Answer 2

As much a I think , by unset, you are removing a part of array, making it non sequential Thus it might be converted into object
I guess the above line was bit unclear, so consider this example,
function ep($f)
{
echo "<br><pre><code>";
print_r($f);
echo "</code></pre><br";
}
$t = array("a","b","c");
ep(json_encode($t));
unset($t[1]);
ep(json_encode($t));
Forget the function ep.On line 1 , we declare a sequential array and print it, as it is sequential it prints as an array. On line 2, we break the sequence. So printing it again , though it is an array, (*it maybe PHP's function does not know how to convert it) it printed as Object