Laravel Error on submission of data Undefined Index: - php

Question

I'm trying to add data to my cart table by adding a product to cart but instead i get the above error Undefined index:size
code from the responsible controller
public function addToCart(Request $request){
Session::forget('CouponAmount');
Session::forget('CouponCode');
$data = $request->all();
if(empty($data['user_email'])){
$data['user_email']='';
}
$session_id= Session::get('session_id');
if(empty($session_id)){
$session_id = str_random(40);
Session::put('session_id', $session_id);
}
$sizeArr=explode("-",$data['size']);
$countProducts = DB::table('cart')-
>where(['product_id'=>$data['product_id'],
'product_color'=>$data['product_color'],
'size'=>$sizeArr[1], 'session_id'=>$session_id,])->count();
if($countProducts>0){
return redirect()->back()->with('flash_message_error', 'Exact
product already exists in Cart!');
}else {
$getSKU = ProductsAttribute::select('sku')-
>where(['product_id'=>$data['product_id'], 'size'=>$sizeArr[1]])-
>first();
DB::table('cart')->insert(['product_id'=>$data['product_id'],
'product_name'=>$data['product_name'],
'product_code'=>$getSKU->sku,
'product_color'=>$data['product_color'], 'price'=>$data['price'],
'size'=>$sizeArr[1], 'quantity'=>$data['quantity'],
'user_email'=>$data['user_email'], 'session_id'=>$session_id,]);
}
return redirect('cart')->with('flash_message_success', 'Product has
been added to cart!');
}
the blade file where size is input
<h1>{{ $productDetails->product_name }}</h1>
<p>{{ $productDetails->description }}</p>
<div class="dropdown_top">
<div class="dropdown_left">
<select id="size" class="dropdown" tabindex="10"
data-settings='{"wrapperClass":"metro1"}'>
<option value="0">Select size</option>
#foreach ($productDetails->attributes as
$sizes)
<option value="{{ $productDetails->id }}-
{{ $sizes->size }}">{{ $sizes->size }}
</option>
#endforeach
</select>
</div>
instead of being redirected to my cart page I get Undefined index:size

Answer 1

I added this in a comment, but thought I'd eloborate :)
The $request->all() call isn't returning 'size' because the name attribute is missing from your <select> tag in the template. The following should fix it:
<select name="size" id="size" class="dropdown" tabindex="10" data-settings='{"wrapperClass":"metro1"}'>