Alter specific array values based on others in same "row"

Question

I am trying to perform a transformation/calculation on values in a returned SQL object, based on other values in the same row. I cannot find a good reference for this, perhaps I just don't know what I'm looking for; it seems most functions (e.g array_walk) are for applying the same transformation to all values in an entire array? I want to alter just certain values, conditionally.

Here is my simplified attempt; doesn't work, but I think shows what I'm trying to do:

//------CREATE OBJECT-------//
$sql2 = "select internalname, value, adjboolean, adjfactor
         FROM superfilters WHERE id > '0'";

$filterobject = $DBLink->query($sql2);

//------MODIFY OBJECT------//

$input1 = 350;
$input2 = 175;

foreach ($filterobject as $row){
    if ($row['adjboolean'] = 1) {
        $row['value'] += ($row['value'] * ($input1 / $input2 - 1) * $row['adjfactor']);
    }
}

After trying to modify, no errors are thrown, but there is no effect on my row value. I'd prefer to over-write, not create a duplicate array/object, but I could create new if necessary to perform the function.

Huge thanks for any help!

----EDIT---- Ok, so I have now learned that foreach actually works on a copy of my $filterobject, and I must reference in order to modify the actual result object. It seems the following should work

    foreach ($filterobject as &$row){

However, I get the error "An iterator cannot be used with foreach by reference". So, now I'm working on that...

Answer 1

You need to add an & to let $row be updated by reference, otherwise it will get overwritten each time you loop and won't persist outside of the foreach.

Also, I assume your adjboolean check should be a comparison rather than an assignment? Use == instead of =.

foreach ($filterobject as &$row){
    if ($row['adjboolean'] == 1) {
        $row['value'] += ($row['value'] * ($input1 / $input2 - 1) * $row['adjfactor']);
    }
}

FYI, array_walk() will walk as well, you will just need to use your external variables to allow them to be accessible inside the callback's scope:

array_walk(
    $filterobject,
    function(&$row, $key) use($input1, $input2) {
        if ($row['adjboolean'] == 1) {
            $row['value'] += ($row['value'] * ($input1 / $input2 - 1) * $row['adjfactor']);
        }
    }
);

Examples here.