Add element to PHP associative array in loop - php

Question

I've looked but can't find an answer for my specific use case. I want to add an element to a multidimensional array while looping through it. What I have before the loop:
Array
(
[fname] => Monty
[lname] => Python
[phone] => 555 555 1212
[email] => a#b.com
[modelList] => Array
(
[0] => Array
(
[id] => 1
[modelName] => X-Wing
[remarks] =>
[htmlRemarks] =>
[category] => Vehicles
[catID] => 178
[attachedToBase] => 1
[oversized] => 0
)
)
)
In code, I'm looping through the [modelList] array and after doing some database operations what I want to do is append new elements to each model array - in the case below, the [dbID]:
Array
(
[fname] => Monty
[lname] => Python
[phone] => 555 555 1212
[email] => a#b.com
[modelList] => Array
(
[0] => Array
(
[id] => 1
[modelName] => X-Wing
[remarks] =>
[htmlRemarks] =>
[category] => Vehicles
[catID] => 178
[attachedToBase] => 1
[oversized] => 0
[dbID] => 907
)
)
)
All inputs are from a form POST, and in my php handler:
// Loop thru model entries
$modelList = json_decode($_POST["modelList"], TRUE);
foreach($modelList as $model) {
(do some work)
// Add the new element
array_push($model['dbID'], $newID);
}
But this throws an error:
PHP Warning: array_push() expects parameter 1 to be array, null given
How can I add the new element to the sub-array?

Answer 1

array_push
Push one or more elements onto the end of array
You can't add a key value item to an array using array_push.
Use this instead :
foreach ($modelList as $key => $model){
$modelList[$key]['dbID'] = $newID;
}

Answer 2

Based on your snippet with the loop are you trying to actually update the dbID?
If so, you should change the logic to:
foreach ($modelList as $key => $model) {
(do some work)
$modelList[$key]['dbID'] = $newID;
}
Why:
you cannot change contents of the array you are looping over (unless accessed by reference)
in your example code $model['dbID'] is number 907 which is not an array, hence the error message

Answer 3

Found it - I needed to use a reference to $model in order to update it
// Loop thru model entries
$modelList = json_decode($_POST["modelList"], TRUE);
foreach($modelList as &$model) {
(do some work)
// Add the new element
$model['dbID'] = $newID;
}
unset($model);