Passing a select option to a controller in laravel

I am trying to pass a select option to a controller this way

**product.blade.php**
Category <br>
<select name="category_name" id="">
 @foreach ($categories as $category)
   <option value=""></option>
 @endforeach
</select><br>

ProductController.php

$product = new Product;
$category_name = $request->category_name;
$category_id =DB::table('categories')->where('category_name',$request->category_name)->value('id');
$vendor_id = DB::table('vendors')->where('user_id',$user_id)->value('id');

echo $category_name;

It does not echo anything yet. What Have I done wrong?

via Chebli Mohamed