Unset an object from an array and then decode returns incorrect format php

Question

I have an array of "components" stored in a database in json format, I want to delete (unset) an item and then save it back to the database.

The problem I have is when I unset the item it adds extra numbers for the location of the array when I use json_encode() and has a different format. So I can't read it correctly.

Below is how it is stored correctl:y Json string then Array

[{"id":"1","component":"crank","brand":"part1","date_":"13/11/2019"},{"id":"2","component":"rim","date_":"13/11/2019","location":"Front","servicetype":"part 2"},{"id":"3","component":"bar","brand":"part 3","date_":"13/11/2019"}]

Array
(
    [0] => stdClass Object
        (
            [id] => 1
            [component] => crank
            [brand] => part1
            [date_] => 13/11/2019
        )

    [1] => stdClass Object
        (
            [id] => 2
            [component] => rim
            [date_] => 13/11/2019
            [location] => Front
            [servicetype] => part 2
        )

    [2] => stdClass Object
        (
            [id] => 3
            [component] => bar
            [brand] => part 3
            [date_] => 13/11/2019
        )

)

---

Below is the json_encoded result after I unset the item with id 2. It doesn't have the square brackets either side, adds a curly bracket to the end and adds array locations.

{"1":{"id":"2","component":"rim","date_":"13/11/2019","location":"Front","servicetype":"part 2"},"2":{"id":"3","component":"bar","brand":"part 3","date_":"13/11/2019"}}

---

The code below is what I have for sorting the data and removing the item:

<?php

$jsonData = '[{"id":"1","component":"crank","brand":"part1","date_":"13\/11\/2019"},{"id":"2","component":"rim","date_":"13\/11\/2019","location":"Front","servicetype":"part 2"},{"id":"3","component":"bar","brand":"part 3","date_":"13\/11\/2019"}]';

$id = 2;

$dataToSort = json_decode($jsonData);

foreach($dataToSort as $Key => $element) {
    if ($element->id == $id) {
        unset($dataToSort[$Key]);
        echo $id . " Deleted\n";
    }
}

$newJsonData = json_encode($dataToSort);

echo $newJsonData;

Result below" echo $newJsonData:

{"1":{"id":"2","component":"rim","date_":"13\/11\/2019","location":"Front","servicetype":"part 2"},"2":{"id":"3","component":"bar","brand":"part 3","date_":"13\/11\/2019"}}

Answer 1

The behaviour you are seeing is because you cannot represent an array with keys that are not consecutive starting with 0 as an array in JSON, so the array has to take an object form (eg when you delete the middle element you get {"0":{...}, "2":{...}} . To work around that and get the result you desire, use array_values to re-index $dataToSort starting at 0:

$newJsonData = json_encode(array_values($dataToSort));

Output:

[
    {
        "id": "1",
        "component": "crank",
        "brand": "part1",
        "date_": "13\/11\/2019"
    },
    {
        "id": "3",
        "component": "bar",
        "brand": "part 3",
        "date_": "13\/11\/2019"
    }
]

Demo on 3v4l.org