解析：在获取之前检查对象是否存在

I have a column of type array. It stores pointers to other objects. So in my loop I have something like this:

foreach ($artworkArr as $a) {
    $a->fetch();
    $artworkName[] = $a->get('title');
}

Problem here is, fetch immediately throws an exception if the pointer points to an invalid object.

How can I check if the object exists before calling the fetch method?

Just try with:

foreach ($artworkArr as $a) {
    if ($a instanceof ExpectedClass) {
        $a->fetch();
        $artworkName[] = $a->get('title');
    }
}

Or if you don't know the ExpectedClass, you can use method_exists on the $a object:

method_exists($a, 'fetch')