I am using an api for a shopping cart that has some complex json (very complicated to me) data structured like in my screenshot below. In this scenario in my code I am trying to fix an error which I am going to explain by illustrating the data and how its structured as I am very new to JSON and arrays.

This is from the Visual Studio json reader of the data that belongs to an order placed by a customer. This item at the index of [0] has a customFields which has a value.

When a customer completes a purchase, some items they bought can have custom fields, like the size of a shirt (Large) or (Medium) or (Small) etc... In the JSON these customFields have a value which in this case is the size of the shirt for me to display at the thank you page so the customer knows what size he bought. Essentially I am trying to have the data ready to pass to the thank you page view.

When I am calling for these items in my controller, the code only works if ALL the items that were purchased have a customFields. If the customer buys something like a coffee mug that has NO custom fields, then the application breaks because I guess my code is only accounting for items that actually have customFields.

This is the code that I have so far that only works when ALL items that were purchased have a custom field. This is inside my controller.

public ActionResult Thankyou(string token)
    { 
       int itemsCountAddedToCart = (int)obj["items"].Count();

            var items = obj["items"].Select(o =>
            new Item
            {
                name = o["name"].ToString(),
                quantity = int.Parse(o["quantity"].ToString()),
                price = double.Parse(o["price"].ToString()),
                image = o["image"].ToString(),
                url = o["url"].ToString(),

                //This customFields is what works, but only if all items had custom fields.
                customFields = o["customFields"][0]["value"].ToString(),
                                        
            });

            thankYouViewModel.OrderItems = items;
     }



//ThankYou View Model that loads hold the data to be able to show in the view.
public class ThankYouViewModel
{
    public IEnumerable<Item> OrderItems { get; set; }
}

public class Item
{        
    public string name { get; set; }
    public double price { get; set; }
    public int quantity { get; set; }
    public string image { get; set; }
    public string url { get; set; }

    //customFields
    public string customFields { get; set; }
}

So that code above works, but breaks when I have items that do not have customFields. This is the error that I get:

System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index'

So how should my code look where its currently breaking so that it can account for situations where one of the items from the JSON does not have a customFields attribute? I am very stuck and have tried to add some conditional statements but did not work because I am dealing with some complex json I do not understand very well yet.

CodePudding user response：

If you want to forget the possibility of more than one element in the customFields array, and only cast the first element value to a string, then use this:

 customFields = (o["customFields"] == null || o["customFields"].Count() == 0)?null:o["customFields"][0]["value"].ToString(),

CodePudding user response：

With customFields = o["customFields"][0]["value"].ToString(), you directly receive the value from the customFields Array. If there is no Array in your case then there is nothing to get.

I would recommend you to check if your customFields exists:

var item = new Item ();
item.name  = o["name"].ToString();
item.quantity  = int.Parse(o["quantity"].ToString());
item.price = double.Parse(o["price"].ToString());
item.image = o["image"].ToString();
item.url = o["image"].ToString();

if(o["customFields"] != null)
{             
   item.customFields = o["customFields"][0]["value"].ToString();
}