How to refer to the property of an object without knowing this property?

Question

PHP

How to refer to item by template

foreach ($model as $item){
            for ($i = 0; $i <= count($pattern); $i++){
                 //должно выглядеть вот так  $item->catalog->name и тд.
                $data[] = $item->$pattern[$i];
            }
        }

this is what is being sent

writeFromModel($model, [
            "catalog->name",
            "catalog->article"
        ]);

and in name there must be an array of name, arcticel

in such an implementation gives an error "Array to string conversion"
is it possible to implement this in php? And How?

Answer 1

The semantics of the task is very bad (catalog in the catalog, does the catalog have a product? One? :)
But in general, on the knee, how to get the nested depth values

<?php

$catalog = new stdClass();
$catalog->product = new stdClass();
$catalog->product->item = 'Short';
$catalog->product->model = 'Adidas';

$catalogPaths = ['product.item', 'product.model'];


function extractValuesByPath(object $obj, array $paths) {
    return array_reduce($paths, function(array $values, string $pattern) use($obj) {
        $values[] = extractPathValue($obj, $pattern);
        return $values;
    }, []);
}

function extractPathValue($obj, $pattern) {
    $paths = explode('.', $pattern);
    
    foreach($paths as $path) {
        if (!property_exists($obj, $path)) {
            // Можно нулл вернуть или к пример `undefined $path`
            throw new InvalidArgumentException('Нет такого свойства во входящих данных!');
        }
    
        $obj = $obj->$path;
    }
    
    return $obj;
}

$res = extractValuesByPath($catalog, $catalogPaths);
var_dump($res);
// [
//       'Short',
//       'Adidas',
// ]