在值消失后设置Foreach（）值

I am trying to add a new key to an existing numerical indexed array using a foreach() loop. I wrote this piece of code:

foreach($new['WidgetInstanceSetting'] as $row){
        $row['random_key'] = $this->__str_rand(32, 'alphanum'); 
        debug($row);
    }
    debug($new);

The first debug() works as I expected: the 'random_key' is created in the $new array. Now, the problem is that the second debug() shows the $new array, but without the newly added key. Why is this happening? How can I solve this problem?

$row ends up being a copy in the scope of the foreach block, so you really are modifying a copy of it and not what's in the original array at all.

Stick a & in your foreach to modify the $row array within your $new array by reference:

foreach($new['WidgetInstanceSetting'] as &$row){

And as user576875 says, delete the reference to $row in case you use that variable again to avoid unwanted behavior, because PHP leaves it around:

foreach($new['WidgetInstanceSetting'] as &$row){
    $row['random_key'] = $this->__str_rand(32, 'alphanum'); 
    debug($row);
}
unset($row);
debug($new);

you are not creating random_key in $new array you are creating it in $row

You need to access the element by reference if you want to modify if within the array, as follows:

foreach($new['WidgetInstanceSetting'] as &$row) {
    $row['random_key'] = $this->__str_rand(32, 'alphanum'); 
}

Use the & to get a by reference value that you can change.

foreach($new['WidgetInstanceSetting'] as &$row){
        $row['random_key'] = $this->__str_rand(32, 'alphanum'); 
        debug($row);
    }
    debug($new);