ErrorException in mycontroller on line 137 Undefined offset: 2 - laravel-5

Question

I am getting this exception: Undefined offset: 2 when inserting a multidimensional array in the database. This is my loop at which the error is pointing at:
$order_details = [];
for($i= 0; $i < count($product); $i++){
$order_details[] = [
'order_id' => $orders->id,
'product_id' => $product['product_id'][$i],
'units'=>4,
'quantity' => $product['quantity'][$i],
'unit_price' => $product['price'][$i],
'product_discount_id'=>0,
'amount' => $product['amount'][$i],
];
}
When I echo my array seems to look fine:
Array ( [product_id] => Array ( [0] => 7 [1] => 1 ) [quantity] => Array ( [0] => 2 [1] => 1 ) [price] => Array ( [0] => 200.00 [1] => 700.00 ) [amount] => Array ( [0] => 400 [1] => 700 ) )
The undefined offset value alternates depending on how many items from the shopping cart are passed to the loop. For example if there are 3 items the error is set to Undefined offset:3
Its like I cannot find out the real mole. I have searched the web I have not managed any way out.
Any assistance Kindly. what May I doing wrong?

Answer 1

The errors you are getting are about not having an element with index of count($product).
You should just use:
for($i= 0; $i <count($product)-1; $i++)
This way you loop will be fine.

Answer 2

That's kind of an odd array structure. You'd have a much easier time working with the data if you rearranged it like this so you have an item per product:
$products = [
[
'product_id' => 7,
'quantity' => 2,
'price' => 200.00,
'amount' => 400
],
[
'product_id' => 1,
'quantity' => 1,
'price' => 700.00,
'amount' => 700
]
];
Then you can just foreach over the products.
The fix for your problem though is this for($i= 0; $i <= count($product); $i++)