Laravel Import a Json file in two different tables in one single process

I have a Json File with the following structure:

"products": [
    {
      "sku": 3953367,
      "productId": 1219609308595,
      "name": "Samsung - Galaxy Core Prime 4G LTE with 8GB Memory Cell Phone - Charcoal gray (Verizon)",
      "relatedProducts": [
        {
          "sku": 7664117
        },
        {
          "sku": 2819038
        },
        {
          "sku": 4806009
        }
      ],
      "salesRankShortTerm": 14593,
    }
  ]

To store those details and import the data to a mysql database i created 2 tables:

1. table products (for sku, productID, name and salesRankShortTerm.)
2. table products_related (for relatedProducts and each Sku of products related to the main product)

My idea is to insert into:

• Table products: create a record of ->sku and productname. eg: 3953367, "Samsung - Galaxy Core Prime 4G LTE with 8GB Memory Cell Phone - Charcoal gray (Verizon)"
• Table products_related: create a record of ->sku (same field as sku in products table) and each Sku of relatedproducts. eg: 3953367, 7664117.

I created the following code:

$json = File::get("/json/cell-1.json");
$data = json_decode($json);
$array1 = (array) $data;

// foreach to import into table products
foreach ($array1['products'] as $obj) {
    DB::table('products')->insert(array(
        'productName' => ((isset($obj->name) ? $obj->name : null)),
        'productSku' => ((isset($obj->sku) ? $obj->sku : 1)),
        ..etc
    ));

// foreach to import into table products_related
foreach ($array1['products'] as $obj2) {
    DB::table('products_related')->insert(array(
        'productId' => ((isset($obj2->sku) ? $obj2->sku : null)),
        'sku' => ((isset($obj2->relatedProduct->sku) ? $obj2->relatedProduct->sku : null))
    ));
    }
}

information contained in array1 as $obj1 -> worked perfect, each product (sku, productID, name and salesRankShortTerm) is stored in products table.

details in array1 as $obj2 -> not working ok. each product sku is stored in products related table but not each relatedProducts->sku. its like the foreach of "relatedProducts": [] is not taken into consideration. Additionally if I write $array1['products']['relatedProducts'] the code response is [ErrorException] Undefined Index: relatedProducts.

My question are:

its possible to store all the information in different tables in one run process?

or

I have to import first the information to products and then: use each sku of products table to retrieve and save each sku of relatedProducts into products_related table?

any help appreciated.

via s_h