Question

I have a PHP object retrieved from MySQL.

I can retrieve the values for each object by going through a foreach loop and using the => operator. What I would like to do is apply some logic prior to the foreach loop and potentially to edit/delete some of the rows.

How would I go about changing the value of one of the items, for example question_id for object 1? Also how would I loop through each object and delete it if a certain condition is met? How do I then insert a new object?

Is there a tutorial somewhere that I can read, I can do most stuff with arrays but objects are new to me.

Thanks in advance.

Array ( 
    [0] => stdClass Object ( 
        [question_id] => 1 
        [question_type] => multiple_choice 
        [question_unit] => 7 
        [question_difficulty] => 56.5956047853 
    ) 
    [1] => stdClass Object ( 
        [question_id] => 2 
        [question_type] => multiple_choice 
        [question_unit] => 7 
        [question_difficulty] => 54.665002232  
    ) 
    [2] => stdClass Object ( 
        [question_id] => 3 
        [question_type] => multiple_choice 
        [question_unit] => 7 
        [question_difficulty] => 55.2923002984 
    ) 
)

Answer 1

You can delete object properties using unset():

It is possible to unset even object properties visible in current context.

http://php.net/manual/en/function.unset.php

unset($array[1]->question_type);

---

If you want to loop through the object and manipulate it, you can use foreach() and pass the $obj by reference using &.

For example, if you want to remove all question_id keys if it’s equal to 3, use this:

foreach ($array as &$obj) {
    if ($obj->question_id == 3) unset($obj->question_id);
}

Alternatively, if you want to remove the whole object, you could do it like this:

foreach ($array as &$obj) {
    if ($obj->question_id == 3) unset($obj);
}

---

Update

It seems passing by reference does not work (at least not in your case), so you could try this:

$c = count($questions);
for ($i=0; $i<$c; $i++) {
    if ($questions[$i]->question_id == 3) unset($questions[$i]);
}